iterator.gen.go

// Generated by tmpl
// https://github.com/benbjohnson/tmpl
//
// DO NOT EDIT!
// Source: iterator.gen.go.tmpl

package query

import (
	"container/heap"
	"context"
	"io"
	"sort"
	"sync"
	"time"

	"github.com/gogo/protobuf/proto"
	"github.com/influxdata/influxql"
)

// DefaultStatsInterval is the default value for IteratorEncoder.StatsInterval.
const DefaultStatsInterval = time.Second

// FloatIterator represents a stream of float points.
type FloatIterator interface {
	Iterator
	Next() (*FloatPoint, error)
}

// newFloatIterators converts a slice of Iterator to a slice of FloatIterator.
// Drop and closes any iterator in itrs that is not a FloatIterator and cannot
// be cast to a FloatIterator.
func newFloatIterators(itrs []Iterator) []FloatIterator {
	a := make([]FloatIterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case FloatIterator:
			a = append(a, itr)
		default:
			itr.Close()
		}
	}
	return a
}

// bufFloatIterator represents a buffered FloatIterator.
type bufFloatIterator struct {
	itr FloatIterator
	buf *FloatPoint
}

// newBufFloatIterator returns a buffered FloatIterator.
func newBufFloatIterator(itr FloatIterator) *bufFloatIterator {
	return &bufFloatIterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *bufFloatIterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *bufFloatIterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *bufFloatIterator) peek() (*FloatPoint, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *bufFloatIterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *bufFloatIterator) Next() (*FloatPoint, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *bufFloatIterator) NextInWindow(startTime, endTime int64) (*FloatPoint, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *bufFloatIterator) unread(v *FloatPoint) { itr.buf = v }

// floatMergeIterator represents an iterator that combines multiple float iterators.
type floatMergeIterator struct {
	inputs []FloatIterator
	heap   *floatMergeHeap
	init   bool

	closed bool
	mu     sync.RWMutex

	// Current iterator and window.
	curr   *floatMergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// newFloatMergeIterator returns a new instance of floatMergeIterator.
func newFloatMergeIterator(inputs []FloatIterator, opt IteratorOptions) *floatMergeIterator {
	itr := &floatMergeIterator{
		inputs: inputs,
		heap: &floatMergeHeap{
			items: make([]*floatMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBufFloatIterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &floatMergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *floatMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *floatMergeIterator) Close() error {
	itr.mu.Lock()
	defer itr.mu.Unlock()

	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	itr.closed = true
	return nil
}

// Next returns the next point from the iterator.
func (itr *floatMergeIterator) Next() (*FloatPoint, error) {
	itr.mu.RLock()
	defer itr.mu.RUnlock()
	if itr.closed {
		return nil, nil
	}

	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*floatMergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*floatMergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			tags := p.Tags.Subset(itr.heap.opt.Dimensions)
			itr.window.name, itr.window.tags = p.Name, tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if tags := p.Tags.Subset(itr.heap.opt.Dimensions); window.tags != tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// floatMergeHeap represents a heap of floatMergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type floatMergeHeap struct {
	opt   IteratorOptions
	items []*floatMergeHeapItem
}

func (h *floatMergeHeap) Len() int      { return len(h.items) }
func (h *floatMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *floatMergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() < yTags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() > yTags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}

func (h *floatMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*floatMergeHeapItem))
}

func (h *floatMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type floatMergeHeapItem struct {
	itr *bufFloatIterator
}

// floatSortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type floatSortedMergeIterator struct {
	inputs []FloatIterator
	heap   *floatSortedMergeHeap
	init   bool
}

// newFloatSortedMergeIterator returns an instance of floatSortedMergeIterator.
func newFloatSortedMergeIterator(inputs []FloatIterator, opt IteratorOptions) Iterator {
	itr := &floatSortedMergeIterator{
		inputs: inputs,
		heap: &floatSortedMergeHeap{
			items: make([]*floatSortedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &floatSortedMergeHeapItem{itr: input})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *floatSortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *floatSortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *floatSortedMergeIterator) Next() (*FloatPoint, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *floatSortedMergeIterator) pop() (*FloatPoint, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*floatSortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	if len(itr.heap.items) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(itr.heap).(*floatSortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(itr.heap, item)
	}

	return p, nil
}

// floatSortedMergeHeap represents a heap of floatSortedMergeHeapItems.
// Items are sorted with the following priority:
//     - By their measurement name;
//     - By their tag keys/values;
//     - By time; or
//     - By their Aux field values.
//
type floatSortedMergeHeap struct {
	opt   IteratorOptions
	items []*floatSortedMergeHeapItem
}

func (h *floatSortedMergeHeap) Len() int      { return len(h.items) }
func (h *floatSortedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *floatSortedMergeHeap) Less(i, j int) bool {
	x, y := h.items[i].point, h.items[j].point

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
			return xTags.ID() < yTags.ID()
		}

		if x.Time != y.Time {
			return x.Time < y.Time
		}

		if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
			for i := 0; i < len(x.Aux); i++ {
				v1, ok1 := x.Aux[i].(string)
				v2, ok2 := y.Aux[i].(string)
				if !ok1 || !ok2 {
					// Unsupported types used in Aux fields. Maybe they
					// need to be added here?
					return false
				} else if v1 == v2 {
					continue
				}
				return v1 < v2
			}
		}
		return false // Times and/or Aux fields are equal.
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
		return xTags.ID() > yTags.ID()
	}

	if x.Time != y.Time {
		return x.Time > y.Time
	}

	if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
		for i := 0; i < len(x.Aux); i++ {
			v1, ok1 := x.Aux[i].(string)
			v2, ok2 := y.Aux[i].(string)
			if !ok1 || !ok2 {
				// Unsupported types used in Aux fields. Maybe they
				// need to be added here?
				return false
			} else if v1 == v2 {
				continue
			}
			return v1 > v2
		}
	}
	return false // Times and/or Aux fields are equal.
}

func (h *floatSortedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*floatSortedMergeHeapItem))
}

func (h *floatSortedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type floatSortedMergeHeapItem struct {
	point *FloatPoint
	err   error
	itr   FloatIterator
}

// floatIteratorScanner scans the results of a FloatIterator into a map.
type floatIteratorScanner struct {
	input        *bufFloatIterator
	err          error
	keys         []influxql.VarRef
	defaultValue interface{}
}

// newFloatIteratorScanner creates a new IteratorScanner.
func newFloatIteratorScanner(input FloatIterator, keys []influxql.VarRef, defaultValue interface{}) *floatIteratorScanner {
	return &floatIteratorScanner{
		input:        newBufFloatIterator(input),
		keys:         keys,
		defaultValue: defaultValue,
	}
}

func (s *floatIteratorScanner) Peek() (int64, string, Tags) {
	if s.err != nil {
		return ZeroTime, "", Tags{}
	}

	p, err := s.input.peek()
	if err != nil {
		s.err = err
		return ZeroTime, "", Tags{}
	} else if p == nil {
		return ZeroTime, "", Tags{}
	}
	return p.Time, p.Name, p.Tags
}

func (s *floatIteratorScanner) ScanAt(ts int64, name string, tags Tags, m map[string]interface{}) {
	if s.err != nil {
		return
	}

	p, err := s.input.Next()
	if err != nil {
		s.err = err
		return
	} else if p == nil {
		s.useDefaults(m)
		return
	} else if p.Time != ts || p.Name != name || !p.Tags.Equals(&tags) {
		s.useDefaults(m)
		s.input.unread(p)
		return
	}

	if k := s.keys[0]; k.Val != "" {
		if p.Nil {
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		} else {
			m[k.Val] = p.Value
		}
	}
	for i, v := range p.Aux {
		k := s.keys[i+1]
		switch v.(type) {
		case float64, int64, uint64, string, bool:
			m[k.Val] = v
		default:
			// Insert the fill value if one was specified.
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		}
	}
}

func (s *floatIteratorScanner) useDefaults(m map[string]interface{}) {
	if s.defaultValue == SkipDefault {
		return
	}
	for _, k := range s.keys {
		if k.Val == "" {
			continue
		}
		m[k.Val] = castToType(s.defaultValue, k.Type)
	}
}

func (s *floatIteratorScanner) Stats() IteratorStats { return s.input.Stats() }
func (s *floatIteratorScanner) Err() error           { return s.err }
func (s *floatIteratorScanner) Close() error         { return s.input.Close() }

// floatParallelIterator represents an iterator that pulls data in a separate goroutine.
type floatParallelIterator struct {
	input FloatIterator
	ch    chan floatPointError

	once    sync.Once
	closing chan struct{}
	wg      sync.WaitGroup
}

// newFloatParallelIterator returns a new instance of floatParallelIterator.
func newFloatParallelIterator(input FloatIterator) *floatParallelIterator {
	itr := &floatParallelIterator{
		input:   input,
		ch:      make(chan floatPointError, 256),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *floatParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *floatParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *floatParallelIterator) Next() (*FloatPoint, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *floatParallelIterator) monitor() {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()
		if p != nil {
			p = p.Clone()
		}

		select {
		case <-itr.closing:
			return
		case itr.ch <- floatPointError{point: p, err: err}:
		}
	}
}

type floatPointError struct {
	point *FloatPoint
	err   error
}

// floatLimitIterator represents an iterator that limits points per group.
type floatLimitIterator struct {
	input FloatIterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// newFloatLimitIterator returns a new instance of floatLimitIterator.
func newFloatLimitIterator(input FloatIterator, opt IteratorOptions) *floatLimitIterator {
	return &floatLimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *floatLimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *floatLimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *floatLimitIterator) Next() (*FloatPoint, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			continue
		}

		return p, nil
	}
}

type floatFillIterator struct {
	input     *bufFloatIterator
	prev      FloatPoint
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name   string
		tags   Tags
		time   int64
		offset int64
	}
}

func newFloatFillIterator(input FloatIterator, expr influxql.Expr, opt IteratorOptions) *floatFillIterator {
	if opt.Fill == influxql.NullFill {
		if expr, ok := expr.(*influxql.Call); ok && expr.Name == "count" {
			opt.Fill = influxql.NumberFill
			opt.FillValue = float64(0)
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &floatFillIterator{
		input:     newBufFloatIterator(input),
		prev:      FloatPoint{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *floatFillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *floatFillIterator) Close() error         { return itr.input.Close() }

func (itr *floatFillIterator) Next() (*FloatPoint, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.startTime == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	if p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending && itr.window.time <= itr.endTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		} else if !itr.opt.Ascending && itr.window.time >= itr.endTime && itr.endTime != influxql.MinTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.window.time == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.prev = FloatPoint{Nil: true}
	}

	// Check if the point is our next expected point.
CONSTRUCT:
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &FloatPoint{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case influxql.LinearFill:
			if !itr.prev.Nil {
				next, err := itr.input.peek()
				if err != nil {
					return nil, err
				} else if next != nil && next.Name == itr.window.name && next.Tags.ID() == itr.window.tags.ID() {
					interval := int64(itr.opt.Interval.Duration)
					start := itr.window.time / interval
					p.Value = linearFloat(start, itr.prev.Time/interval, next.Time/interval, itr.prev.Value, next.Value)
				} else {
					p.Nil = true
				}
			} else {
				p.Nil = true
			}

		case influxql.NullFill:
			p.Nil = true
		case influxql.NumberFill:
			p.Value, _ = castToFloat(itr.opt.FillValue)
		case influxql.PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time += int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time -= int64(itr.opt.Interval.Duration)
	}

	// Check to see if we have passed over an offset change and adjust the time
	// to account for this new offset.
	if itr.opt.Location != nil {
		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
			diff := itr.window.offset - offset
			if abs(diff) < int64(itr.opt.Interval.Duration) {
				itr.window.time += diff
			}
			itr.window.offset = offset
		}
	}
	return p, nil
}

// floatIntervalIterator represents a float implementation of IntervalIterator.
type floatIntervalIterator struct {
	input FloatIterator
	opt   IteratorOptions
}

func newFloatIntervalIterator(input FloatIterator, opt IteratorOptions) *floatIntervalIterator {
	return &floatIntervalIterator{input: input, opt: opt}
}

func (itr *floatIntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *floatIntervalIterator) Close() error         { return itr.input.Close() }

func (itr *floatIntervalIterator) Next() (*FloatPoint, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	// If we see the minimum allowable time, set the time to zero so we don't
	// break the default returned time for aggregate queries without times.
	if p.Time == influxql.MinTime {
		p.Time = 0
	}
	return p, nil
}

// floatInterruptIterator represents a float implementation of InterruptIterator.
type floatInterruptIterator struct {
	input   FloatIterator
	closing <-chan struct{}
	count   int
}

func newFloatInterruptIterator(input FloatIterator, closing <-chan struct{}) *floatInterruptIterator {
	return &floatInterruptIterator{input: input, closing: closing}
}

func (itr *floatInterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *floatInterruptIterator) Close() error         { return itr.input.Close() }

func (itr *floatInterruptIterator) Next() (*FloatPoint, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count&0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, itr.Close()
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// floatCloseInterruptIterator represents a float implementation of CloseInterruptIterator.
type floatCloseInterruptIterator struct {
	input   FloatIterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func newFloatCloseInterruptIterator(input FloatIterator, closing <-chan struct{}) *floatCloseInterruptIterator {
	itr := &floatCloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *floatCloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *floatCloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *floatCloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *floatCloseInterruptIterator) Next() (*FloatPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// floatReduceFloatIterator executes a reducer for every interval and buffers the result.
type floatReduceFloatIterator struct {
	input    *bufFloatIterator
	create   func() (FloatPointAggregator, FloatPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []FloatPoint
	keepTags bool
}

func newFloatReduceFloatIterator(input FloatIterator, opt IteratorOptions, createFn func() (FloatPointAggregator, FloatPointEmitter)) *floatReduceFloatIterator {
	return &floatReduceFloatIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *floatReduceFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatReduceFloatIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *floatReduceFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// floatReduceFloatPoint stores the reduced data for a name/tag combination.
type floatReduceFloatPoint struct {
	Name       string
	Tags       Tags
	Aggregator FloatPointAggregator
	Emitter    FloatPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *floatReduceFloatIterator) reduce() ([]FloatPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*floatReduceFloatPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)
	}

	// Reverse sort points by name & tag.
	// This ensures a consistent order of output.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Sort(reverseStringSlice(keys))

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]FloatPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(floatPointsByTime(a)))
	}
	return a, nil
}

// floatStreamFloatIterator streams inputs into the iterator and emits points gradually.
type floatStreamFloatIterator struct {
	input  *bufFloatIterator
	create func() (FloatPointAggregator, FloatPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*floatReduceFloatPoint
	points []FloatPoint
}

// newFloatStreamFloatIterator returns a new instance of floatStreamFloatIterator.
func newFloatStreamFloatIterator(input FloatIterator, createFn func() (FloatPointAggregator, FloatPointEmitter), opt IteratorOptions) *floatStreamFloatIterator {
	return &floatStreamFloatIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*floatReduceFloatPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatStreamFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatStreamFloatIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *floatStreamFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *floatStreamFloatIterator) reduce() ([]FloatPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []FloatPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// floatReduceIntegerIterator executes a reducer for every interval and buffers the result.
type floatReduceIntegerIterator struct {
	input    *bufFloatIterator
	create   func() (FloatPointAggregator, IntegerPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []IntegerPoint
	keepTags bool
}

func newFloatReduceIntegerIterator(input FloatIterator, opt IteratorOptions, createFn func() (FloatPointAggregator, IntegerPointEmitter)) *floatReduceIntegerIterator {
	return &floatReduceIntegerIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *floatReduceIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatReduceIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *floatReduceIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// floatReduceIntegerPoint stores the reduced data for a name/tag combination.
type floatReduceIntegerPoint struct {
	Name       string
	Tags       Tags
	Aggregator FloatPointAggregator
	Emitter    IntegerPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *floatReduceIntegerIterator) reduce() ([]IntegerPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*floatReduceIntegerPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]IntegerPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(integerPointsByTime(a)))
	}
	return a, nil
}

// floatStreamIntegerIterator streams inputs into the iterator and emits points gradually.
type floatStreamIntegerIterator struct {
	input  *bufFloatIterator
	create func() (FloatPointAggregator, IntegerPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*floatReduceIntegerPoint
	points []IntegerPoint
}

// newFloatStreamIntegerIterator returns a new instance of floatStreamIntegerIterator.
func newFloatStreamIntegerIterator(input FloatIterator, createFn func() (FloatPointAggregator, IntegerPointEmitter), opt IteratorOptions) *floatStreamIntegerIterator {
	return &floatStreamIntegerIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*floatReduceIntegerPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatStreamIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatStreamIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *floatStreamIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *floatStreamIntegerIterator) reduce() ([]IntegerPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []IntegerPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// floatReduceUnsignedIterator executes a reducer for every interval and buffers the result.
type floatReduceUnsignedIterator struct {
	input    *bufFloatIterator
	create   func() (FloatPointAggregator, UnsignedPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []UnsignedPoint
	keepTags bool
}

func newFloatReduceUnsignedIterator(input FloatIterator, opt IteratorOptions, createFn func() (FloatPointAggregator, UnsignedPointEmitter)) *floatReduceUnsignedIterator {
	return &floatReduceUnsignedIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *floatReduceUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatReduceUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *floatReduceUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// floatReduceUnsignedPoint stores the reduced data for a name/tag combination.
type floatReduceUnsignedPoint struct {
	Name       string
	Tags       Tags
	Aggregator FloatPointAggregator
	Emitter    UnsignedPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *floatReduceUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*floatReduceUnsignedPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]UnsignedPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(unsignedPointsByTime(a)))
	}
	return a, nil
}

// floatStreamUnsignedIterator streams inputs into the iterator and emits points gradually.
type floatStreamUnsignedIterator struct {
	input  *bufFloatIterator
	create func() (FloatPointAggregator, UnsignedPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*floatReduceUnsignedPoint
	points []UnsignedPoint
}

// newFloatStreamUnsignedIterator returns a new instance of floatStreamUnsignedIterator.
func newFloatStreamUnsignedIterator(input FloatIterator, createFn func() (FloatPointAggregator, UnsignedPointEmitter), opt IteratorOptions) *floatStreamUnsignedIterator {
	return &floatStreamUnsignedIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*floatReduceUnsignedPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatStreamUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatStreamUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *floatStreamUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *floatStreamUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []UnsignedPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// floatReduceStringIterator executes a reducer for every interval and buffers the result.
type floatReduceStringIterator struct {
	input    *bufFloatIterator
	create   func() (FloatPointAggregator, StringPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []StringPoint
	keepTags bool
}

func newFloatReduceStringIterator(input FloatIterator, opt IteratorOptions, createFn func() (FloatPointAggregator, StringPointEmitter)) *floatReduceStringIterator {
	return &floatReduceStringIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *floatReduceStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatReduceStringIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *floatReduceStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// floatReduceStringPoint stores the reduced data for a name/tag combination.
type floatReduceStringPoint struct {
	Name       string
	Tags       Tags
	Aggregator FloatPointAggregator
	Emitter    StringPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *floatReduceStringIterator) reduce() ([]StringPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*floatReduceStringPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]StringPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(stringPointsByTime(a)))
	}
	return a, nil
}

// floatStreamStringIterator streams inputs into the iterator and emits points gradually.
type floatStreamStringIterator struct {
	input  *bufFloatIterator
	create func() (FloatPointAggregator, StringPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*floatReduceStringPoint
	points []StringPoint
}

// newFloatStreamStringIterator returns a new instance of floatStreamStringIterator.
func newFloatStreamStringIterator(input FloatIterator, createFn func() (FloatPointAggregator, StringPointEmitter), opt IteratorOptions) *floatStreamStringIterator {
	return &floatStreamStringIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*floatReduceStringPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatStreamStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatStreamStringIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *floatStreamStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *floatStreamStringIterator) reduce() ([]StringPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []StringPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// floatReduceBooleanIterator executes a reducer for every interval and buffers the result.
type floatReduceBooleanIterator struct {
	input    *bufFloatIterator
	create   func() (FloatPointAggregator, BooleanPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []BooleanPoint
	keepTags bool
}

func newFloatReduceBooleanIterator(input FloatIterator, opt IteratorOptions, createFn func() (FloatPointAggregator, BooleanPointEmitter)) *floatReduceBooleanIterator {
	return &floatReduceBooleanIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *floatReduceBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatReduceBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *floatReduceBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// floatReduceBooleanPoint stores the reduced data for a name/tag combination.
type floatReduceBooleanPoint struct {
	Name       string
	Tags       Tags
	Aggregator FloatPointAggregator
	Emitter    BooleanPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *floatReduceBooleanIterator) reduce() ([]BooleanPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*floatReduceBooleanPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]BooleanPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(booleanPointsByTime(a)))
	}
	return a, nil
}

// floatStreamBooleanIterator streams inputs into the iterator and emits points gradually.
type floatStreamBooleanIterator struct {
	input  *bufFloatIterator
	create func() (FloatPointAggregator, BooleanPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*floatReduceBooleanPoint
	points []BooleanPoint
}

// newFloatStreamBooleanIterator returns a new instance of floatStreamBooleanIterator.
func newFloatStreamBooleanIterator(input FloatIterator, createFn func() (FloatPointAggregator, BooleanPointEmitter), opt IteratorOptions) *floatStreamBooleanIterator {
	return &floatStreamBooleanIterator{
		input:  newBufFloatIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*floatReduceBooleanPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatStreamBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatStreamBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *floatStreamBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *floatStreamBooleanIterator) reduce() ([]BooleanPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []BooleanPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &floatReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateFloat(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// floatDedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type floatDedupeIterator struct {
	input FloatIterator
	m     map[string]struct{} // lookup of points already sent
}

type floatIteratorMapper struct {
	cur    Cursor
	row    Row
	driver IteratorMap   // which iterator to use for the primary value, can be nil
	fields []IteratorMap // which iterator to use for an aux field
	point  FloatPoint
}

func newFloatIteratorMapper(cur Cursor, driver IteratorMap, fields []IteratorMap, opt IteratorOptions) *floatIteratorMapper {
	return &floatIteratorMapper{
		cur:    cur,
		driver: driver,
		fields: fields,
		point: FloatPoint{
			Aux: make([]interface{}, len(fields)),
		},
	}
}

func (itr *floatIteratorMapper) Next() (*FloatPoint, error) {
	if !itr.cur.Scan(&itr.row) {
		if err := itr.cur.Err(); err != nil {
			return nil, err
		}
		return nil, nil
	}

	itr.point.Time = itr.row.Time
	itr.point.Name = itr.row.Series.Name
	itr.point.Tags = itr.row.Series.Tags

	if itr.driver != nil {
		if v := itr.driver.Value(&itr.row); v != nil {
			if v, ok := castToFloat(v); ok {
				itr.point.Value = v
				itr.point.Nil = false
			} else {
				itr.point.Value = 0
				itr.point.Nil = true
			}
		} else {
			itr.point.Value = 0
			itr.point.Nil = true
		}
	}
	for i, f := range itr.fields {
		itr.point.Aux[i] = f.Value(&itr.row)
	}
	return &itr.point, nil
}

func (itr *floatIteratorMapper) Stats() IteratorStats {
	return itr.cur.Stats()
}

func (itr *floatIteratorMapper) Close() error {
	return itr.cur.Close()
}

type floatFilterIterator struct {
	input FloatIterator
	cond  influxql.Expr
	opt   IteratorOptions
	m     map[string]interface{}
}

func newFloatFilterIterator(input FloatIterator, cond influxql.Expr, opt IteratorOptions) FloatIterator {
	// Strip out time conditions from the WHERE clause.
	// TODO(jsternberg): This should really be done for us when creating the IteratorOptions struct.
	n := influxql.RewriteFunc(influxql.CloneExpr(cond), func(n influxql.Node) influxql.Node {
		switch n := n.(type) {
		case *influxql.BinaryExpr:
			if n.LHS.String() == "time" {
				return &influxql.BooleanLiteral{Val: true}
			}
		}
		return n
	})

	cond, _ = n.(influxql.Expr)
	if cond == nil {
		return input
	} else if n, ok := cond.(*influxql.BooleanLiteral); ok && n.Val {
		return input
	}

	return &floatFilterIterator{
		input: input,
		cond:  cond,
		opt:   opt,
		m:     make(map[string]interface{}),
	}
}

func (itr *floatFilterIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *floatFilterIterator) Close() error         { return itr.input.Close() }

func (itr *floatFilterIterator) Next() (*FloatPoint, error) {
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		}

		for i, ref := range itr.opt.Aux {
			itr.m[ref.Val] = p.Aux[i]
		}
		for k, v := range p.Tags.KeyValues() {
			itr.m[k] = v
		}

		if !influxql.EvalBool(itr.cond, itr.m) {
			continue
		}
		return p, nil
	}
}

type floatTagSubsetIterator struct {
	input      FloatIterator
	point      FloatPoint
	lastTags   Tags
	dimensions []string
}

func newFloatTagSubsetIterator(input FloatIterator, opt IteratorOptions) *floatTagSubsetIterator {
	return &floatTagSubsetIterator{
		input:      input,
		dimensions: opt.GetDimensions(),
	}
}

func (itr *floatTagSubsetIterator) Next() (*FloatPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p == nil {
		return nil, nil
	}

	itr.point.Name = p.Name
	if !p.Tags.Equal(itr.lastTags) {
		itr.point.Tags = p.Tags.Subset(itr.dimensions)
		itr.lastTags = p.Tags
	}
	itr.point.Time = p.Time
	itr.point.Value = p.Value
	itr.point.Aux = p.Aux
	itr.point.Aggregated = p.Aggregated
	itr.point.Nil = p.Nil
	return &itr.point, nil
}

func (itr *floatTagSubsetIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *floatTagSubsetIterator) Close() error {
	return itr.input.Close()
}

// newFloatDedupeIterator returns a new instance of floatDedupeIterator.
func newFloatDedupeIterator(input FloatIterator) *floatDedupeIterator {
	return &floatDedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *floatDedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *floatDedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *floatDedupeIterator) Next() (*FloatPoint, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encodeFloatPoint(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// floatReaderIterator represents an iterator that streams from a reader.
type floatReaderIterator struct {
	r   io.Reader
	dec *FloatPointDecoder
}

// newFloatReaderIterator returns a new instance of floatReaderIterator.
func newFloatReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *floatReaderIterator {
	dec := NewFloatPointDecoder(ctx, r)
	dec.stats = stats

	return &floatReaderIterator{
		r:   r,
		dec: dec,
	}
}

// Stats returns stats about points processed.
func (itr *floatReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *floatReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *floatReaderIterator) Next() (*FloatPoint, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &FloatPoint{}
	if err := itr.dec.DecodeFloatPoint(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}

// IntegerIterator represents a stream of integer points.
type IntegerIterator interface {
	Iterator
	Next() (*IntegerPoint, error)
}

// newIntegerIterators converts a slice of Iterator to a slice of IntegerIterator.
// Drop and closes any iterator in itrs that is not a IntegerIterator and cannot
// be cast to a IntegerIterator.
func newIntegerIterators(itrs []Iterator) []IntegerIterator {
	a := make([]IntegerIterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case IntegerIterator:
			a = append(a, itr)
		default:
			itr.Close()
		}
	}
	return a
}

// bufIntegerIterator represents a buffered IntegerIterator.
type bufIntegerIterator struct {
	itr IntegerIterator
	buf *IntegerPoint
}

// newBufIntegerIterator returns a buffered IntegerIterator.
func newBufIntegerIterator(itr IntegerIterator) *bufIntegerIterator {
	return &bufIntegerIterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *bufIntegerIterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *bufIntegerIterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *bufIntegerIterator) peek() (*IntegerPoint, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *bufIntegerIterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *bufIntegerIterator) Next() (*IntegerPoint, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *bufIntegerIterator) NextInWindow(startTime, endTime int64) (*IntegerPoint, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *bufIntegerIterator) unread(v *IntegerPoint) { itr.buf = v }

// integerMergeIterator represents an iterator that combines multiple integer iterators.
type integerMergeIterator struct {
	inputs []IntegerIterator
	heap   *integerMergeHeap
	init   bool

	closed bool
	mu     sync.RWMutex

	// Current iterator and window.
	curr   *integerMergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// newIntegerMergeIterator returns a new instance of integerMergeIterator.
func newIntegerMergeIterator(inputs []IntegerIterator, opt IteratorOptions) *integerMergeIterator {
	itr := &integerMergeIterator{
		inputs: inputs,
		heap: &integerMergeHeap{
			items: make([]*integerMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBufIntegerIterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &integerMergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *integerMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *integerMergeIterator) Close() error {
	itr.mu.Lock()
	defer itr.mu.Unlock()

	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	itr.closed = true
	return nil
}

// Next returns the next point from the iterator.
func (itr *integerMergeIterator) Next() (*IntegerPoint, error) {
	itr.mu.RLock()
	defer itr.mu.RUnlock()
	if itr.closed {
		return nil, nil
	}

	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*integerMergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*integerMergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			tags := p.Tags.Subset(itr.heap.opt.Dimensions)
			itr.window.name, itr.window.tags = p.Name, tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if tags := p.Tags.Subset(itr.heap.opt.Dimensions); window.tags != tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// integerMergeHeap represents a heap of integerMergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type integerMergeHeap struct {
	opt   IteratorOptions
	items []*integerMergeHeapItem
}

func (h *integerMergeHeap) Len() int      { return len(h.items) }
func (h *integerMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *integerMergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() < yTags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() > yTags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}

func (h *integerMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*integerMergeHeapItem))
}

func (h *integerMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type integerMergeHeapItem struct {
	itr *bufIntegerIterator
}

// integerSortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type integerSortedMergeIterator struct {
	inputs []IntegerIterator
	heap   *integerSortedMergeHeap
	init   bool
}

// newIntegerSortedMergeIterator returns an instance of integerSortedMergeIterator.
func newIntegerSortedMergeIterator(inputs []IntegerIterator, opt IteratorOptions) Iterator {
	itr := &integerSortedMergeIterator{
		inputs: inputs,
		heap: &integerSortedMergeHeap{
			items: make([]*integerSortedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &integerSortedMergeHeapItem{itr: input})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *integerSortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *integerSortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *integerSortedMergeIterator) Next() (*IntegerPoint, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *integerSortedMergeIterator) pop() (*IntegerPoint, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*integerSortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	if len(itr.heap.items) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(itr.heap).(*integerSortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(itr.heap, item)
	}

	return p, nil
}

// integerSortedMergeHeap represents a heap of integerSortedMergeHeapItems.
// Items are sorted with the following priority:
//     - By their measurement name;
//     - By their tag keys/values;
//     - By time; or
//     - By their Aux field values.
//
type integerSortedMergeHeap struct {
	opt   IteratorOptions
	items []*integerSortedMergeHeapItem
}

func (h *integerSortedMergeHeap) Len() int      { return len(h.items) }
func (h *integerSortedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *integerSortedMergeHeap) Less(i, j int) bool {
	x, y := h.items[i].point, h.items[j].point

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
			return xTags.ID() < yTags.ID()
		}

		if x.Time != y.Time {
			return x.Time < y.Time
		}

		if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
			for i := 0; i < len(x.Aux); i++ {
				v1, ok1 := x.Aux[i].(string)
				v2, ok2 := y.Aux[i].(string)
				if !ok1 || !ok2 {
					// Unsupported types used in Aux fields. Maybe they
					// need to be added here?
					return false
				} else if v1 == v2 {
					continue
				}
				return v1 < v2
			}
		}
		return false // Times and/or Aux fields are equal.
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
		return xTags.ID() > yTags.ID()
	}

	if x.Time != y.Time {
		return x.Time > y.Time
	}

	if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
		for i := 0; i < len(x.Aux); i++ {
			v1, ok1 := x.Aux[i].(string)
			v2, ok2 := y.Aux[i].(string)
			if !ok1 || !ok2 {
				// Unsupported types used in Aux fields. Maybe they
				// need to be added here?
				return false
			} else if v1 == v2 {
				continue
			}
			return v1 > v2
		}
	}
	return false // Times and/or Aux fields are equal.
}

func (h *integerSortedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*integerSortedMergeHeapItem))
}

func (h *integerSortedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type integerSortedMergeHeapItem struct {
	point *IntegerPoint
	err   error
	itr   IntegerIterator
}

// integerIteratorScanner scans the results of a IntegerIterator into a map.
type integerIteratorScanner struct {
	input        *bufIntegerIterator
	err          error
	keys         []influxql.VarRef
	defaultValue interface{}
}

// newIntegerIteratorScanner creates a new IteratorScanner.
func newIntegerIteratorScanner(input IntegerIterator, keys []influxql.VarRef, defaultValue interface{}) *integerIteratorScanner {
	return &integerIteratorScanner{
		input:        newBufIntegerIterator(input),
		keys:         keys,
		defaultValue: defaultValue,
	}
}

func (s *integerIteratorScanner) Peek() (int64, string, Tags) {
	if s.err != nil {
		return ZeroTime, "", Tags{}
	}

	p, err := s.input.peek()
	if err != nil {
		s.err = err
		return ZeroTime, "", Tags{}
	} else if p == nil {
		return ZeroTime, "", Tags{}
	}
	return p.Time, p.Name, p.Tags
}

func (s *integerIteratorScanner) ScanAt(ts int64, name string, tags Tags, m map[string]interface{}) {
	if s.err != nil {
		return
	}

	p, err := s.input.Next()
	if err != nil {
		s.err = err
		return
	} else if p == nil {
		s.useDefaults(m)
		return
	} else if p.Time != ts || p.Name != name || !p.Tags.Equals(&tags) {
		s.useDefaults(m)
		s.input.unread(p)
		return
	}

	if k := s.keys[0]; k.Val != "" {
		if p.Nil {
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		} else {
			m[k.Val] = p.Value
		}
	}
	for i, v := range p.Aux {
		k := s.keys[i+1]
		switch v.(type) {
		case float64, int64, uint64, string, bool:
			m[k.Val] = v
		default:
			// Insert the fill value if one was specified.
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		}
	}
}

func (s *integerIteratorScanner) useDefaults(m map[string]interface{}) {
	if s.defaultValue == SkipDefault {
		return
	}
	for _, k := range s.keys {
		if k.Val == "" {
			continue
		}
		m[k.Val] = castToType(s.defaultValue, k.Type)
	}
}

func (s *integerIteratorScanner) Stats() IteratorStats { return s.input.Stats() }
func (s *integerIteratorScanner) Err() error           { return s.err }
func (s *integerIteratorScanner) Close() error         { return s.input.Close() }

// integerParallelIterator represents an iterator that pulls data in a separate goroutine.
type integerParallelIterator struct {
	input IntegerIterator
	ch    chan integerPointError

	once    sync.Once
	closing chan struct{}
	wg      sync.WaitGroup
}

// newIntegerParallelIterator returns a new instance of integerParallelIterator.
func newIntegerParallelIterator(input IntegerIterator) *integerParallelIterator {
	itr := &integerParallelIterator{
		input:   input,
		ch:      make(chan integerPointError, 256),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *integerParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *integerParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *integerParallelIterator) Next() (*IntegerPoint, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *integerParallelIterator) monitor() {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()
		if p != nil {
			p = p.Clone()
		}

		select {
		case <-itr.closing:
			return
		case itr.ch <- integerPointError{point: p, err: err}:
		}
	}
}

type integerPointError struct {
	point *IntegerPoint
	err   error
}

// integerLimitIterator represents an iterator that limits points per group.
type integerLimitIterator struct {
	input IntegerIterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// newIntegerLimitIterator returns a new instance of integerLimitIterator.
func newIntegerLimitIterator(input IntegerIterator, opt IteratorOptions) *integerLimitIterator {
	return &integerLimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *integerLimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *integerLimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *integerLimitIterator) Next() (*IntegerPoint, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			continue
		}

		return p, nil
	}
}

type integerFillIterator struct {
	input     *bufIntegerIterator
	prev      IntegerPoint
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name   string
		tags   Tags
		time   int64
		offset int64
	}
}

func newIntegerFillIterator(input IntegerIterator, expr influxql.Expr, opt IteratorOptions) *integerFillIterator {
	if opt.Fill == influxql.NullFill {
		if expr, ok := expr.(*influxql.Call); ok && expr.Name == "count" {
			opt.Fill = influxql.NumberFill
			opt.FillValue = int64(0)
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &integerFillIterator{
		input:     newBufIntegerIterator(input),
		prev:      IntegerPoint{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *integerFillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *integerFillIterator) Close() error         { return itr.input.Close() }

func (itr *integerFillIterator) Next() (*IntegerPoint, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.startTime == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	if p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending && itr.window.time <= itr.endTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		} else if !itr.opt.Ascending && itr.window.time >= itr.endTime && itr.endTime != influxql.MinTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.window.time == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.prev = IntegerPoint{Nil: true}
	}

	// Check if the point is our next expected point.
CONSTRUCT:
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &IntegerPoint{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case influxql.LinearFill:
			if !itr.prev.Nil {
				next, err := itr.input.peek()
				if err != nil {
					return nil, err
				} else if next != nil && next.Name == itr.window.name && next.Tags.ID() == itr.window.tags.ID() {
					interval := int64(itr.opt.Interval.Duration)
					start := itr.window.time / interval
					p.Value = linearInteger(start, itr.prev.Time/interval, next.Time/interval, itr.prev.Value, next.Value)
				} else {
					p.Nil = true
				}
			} else {
				p.Nil = true
			}

		case influxql.NullFill:
			p.Nil = true
		case influxql.NumberFill:
			p.Value, _ = castToInteger(itr.opt.FillValue)
		case influxql.PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time += int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time -= int64(itr.opt.Interval.Duration)
	}

	// Check to see if we have passed over an offset change and adjust the time
	// to account for this new offset.
	if itr.opt.Location != nil {
		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
			diff := itr.window.offset - offset
			if abs(diff) < int64(itr.opt.Interval.Duration) {
				itr.window.time += diff
			}
			itr.window.offset = offset
		}
	}
	return p, nil
}

// integerIntervalIterator represents a integer implementation of IntervalIterator.
type integerIntervalIterator struct {
	input IntegerIterator
	opt   IteratorOptions
}

func newIntegerIntervalIterator(input IntegerIterator, opt IteratorOptions) *integerIntervalIterator {
	return &integerIntervalIterator{input: input, opt: opt}
}

func (itr *integerIntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *integerIntervalIterator) Close() error         { return itr.input.Close() }

func (itr *integerIntervalIterator) Next() (*IntegerPoint, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	// If we see the minimum allowable time, set the time to zero so we don't
	// break the default returned time for aggregate queries without times.
	if p.Time == influxql.MinTime {
		p.Time = 0
	}
	return p, nil
}

// integerInterruptIterator represents a integer implementation of InterruptIterator.
type integerInterruptIterator struct {
	input   IntegerIterator
	closing <-chan struct{}
	count   int
}

func newIntegerInterruptIterator(input IntegerIterator, closing <-chan struct{}) *integerInterruptIterator {
	return &integerInterruptIterator{input: input, closing: closing}
}

func (itr *integerInterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *integerInterruptIterator) Close() error         { return itr.input.Close() }

func (itr *integerInterruptIterator) Next() (*IntegerPoint, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count&0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, itr.Close()
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// integerCloseInterruptIterator represents a integer implementation of CloseInterruptIterator.
type integerCloseInterruptIterator struct {
	input   IntegerIterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func newIntegerCloseInterruptIterator(input IntegerIterator, closing <-chan struct{}) *integerCloseInterruptIterator {
	itr := &integerCloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *integerCloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *integerCloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *integerCloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *integerCloseInterruptIterator) Next() (*IntegerPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// integerReduceFloatIterator executes a reducer for every interval and buffers the result.
type integerReduceFloatIterator struct {
	input    *bufIntegerIterator
	create   func() (IntegerPointAggregator, FloatPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []FloatPoint
	keepTags bool
}

func newIntegerReduceFloatIterator(input IntegerIterator, opt IteratorOptions, createFn func() (IntegerPointAggregator, FloatPointEmitter)) *integerReduceFloatIterator {
	return &integerReduceFloatIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *integerReduceFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerReduceFloatIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *integerReduceFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// integerReduceFloatPoint stores the reduced data for a name/tag combination.
type integerReduceFloatPoint struct {
	Name       string
	Tags       Tags
	Aggregator IntegerPointAggregator
	Emitter    FloatPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *integerReduceFloatIterator) reduce() ([]FloatPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*integerReduceFloatPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]FloatPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(floatPointsByTime(a)))
	}
	return a, nil
}

// integerStreamFloatIterator streams inputs into the iterator and emits points gradually.
type integerStreamFloatIterator struct {
	input  *bufIntegerIterator
	create func() (IntegerPointAggregator, FloatPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*integerReduceFloatPoint
	points []FloatPoint
}

// newIntegerStreamFloatIterator returns a new instance of integerStreamFloatIterator.
func newIntegerStreamFloatIterator(input IntegerIterator, createFn func() (IntegerPointAggregator, FloatPointEmitter), opt IteratorOptions) *integerStreamFloatIterator {
	return &integerStreamFloatIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*integerReduceFloatPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerStreamFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerStreamFloatIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *integerStreamFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *integerStreamFloatIterator) reduce() ([]FloatPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []FloatPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// integerReduceIntegerIterator executes a reducer for every interval and buffers the result.
type integerReduceIntegerIterator struct {
	input    *bufIntegerIterator
	create   func() (IntegerPointAggregator, IntegerPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []IntegerPoint
	keepTags bool
}

func newIntegerReduceIntegerIterator(input IntegerIterator, opt IteratorOptions, createFn func() (IntegerPointAggregator, IntegerPointEmitter)) *integerReduceIntegerIterator {
	return &integerReduceIntegerIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *integerReduceIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerReduceIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *integerReduceIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// integerReduceIntegerPoint stores the reduced data for a name/tag combination.
type integerReduceIntegerPoint struct {
	Name       string
	Tags       Tags
	Aggregator IntegerPointAggregator
	Emitter    IntegerPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *integerReduceIntegerIterator) reduce() ([]IntegerPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*integerReduceIntegerPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]IntegerPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(integerPointsByTime(a)))
	}
	return a, nil
}

// integerStreamIntegerIterator streams inputs into the iterator and emits points gradually.
type integerStreamIntegerIterator struct {
	input  *bufIntegerIterator
	create func() (IntegerPointAggregator, IntegerPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*integerReduceIntegerPoint
	points []IntegerPoint
}

// newIntegerStreamIntegerIterator returns a new instance of integerStreamIntegerIterator.
func newIntegerStreamIntegerIterator(input IntegerIterator, createFn func() (IntegerPointAggregator, IntegerPointEmitter), opt IteratorOptions) *integerStreamIntegerIterator {
	return &integerStreamIntegerIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*integerReduceIntegerPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerStreamIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerStreamIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *integerStreamIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *integerStreamIntegerIterator) reduce() ([]IntegerPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []IntegerPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// integerReduceUnsignedIterator executes a reducer for every interval and buffers the result.
type integerReduceUnsignedIterator struct {
	input    *bufIntegerIterator
	create   func() (IntegerPointAggregator, UnsignedPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []UnsignedPoint
	keepTags bool
}

func newIntegerReduceUnsignedIterator(input IntegerIterator, opt IteratorOptions, createFn func() (IntegerPointAggregator, UnsignedPointEmitter)) *integerReduceUnsignedIterator {
	return &integerReduceUnsignedIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *integerReduceUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerReduceUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *integerReduceUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// integerReduceUnsignedPoint stores the reduced data for a name/tag combination.
type integerReduceUnsignedPoint struct {
	Name       string
	Tags       Tags
	Aggregator IntegerPointAggregator
	Emitter    UnsignedPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *integerReduceUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*integerReduceUnsignedPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]UnsignedPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(unsignedPointsByTime(a)))
	}
	return a, nil
}

// integerStreamUnsignedIterator streams inputs into the iterator and emits points gradually.
type integerStreamUnsignedIterator struct {
	input  *bufIntegerIterator
	create func() (IntegerPointAggregator, UnsignedPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*integerReduceUnsignedPoint
	points []UnsignedPoint
}

// newIntegerStreamUnsignedIterator returns a new instance of integerStreamUnsignedIterator.
func newIntegerStreamUnsignedIterator(input IntegerIterator, createFn func() (IntegerPointAggregator, UnsignedPointEmitter), opt IteratorOptions) *integerStreamUnsignedIterator {
	return &integerStreamUnsignedIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*integerReduceUnsignedPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerStreamUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerStreamUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *integerStreamUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *integerStreamUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []UnsignedPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// integerReduceStringIterator executes a reducer for every interval and buffers the result.
type integerReduceStringIterator struct {
	input    *bufIntegerIterator
	create   func() (IntegerPointAggregator, StringPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []StringPoint
	keepTags bool
}

func newIntegerReduceStringIterator(input IntegerIterator, opt IteratorOptions, createFn func() (IntegerPointAggregator, StringPointEmitter)) *integerReduceStringIterator {
	return &integerReduceStringIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *integerReduceStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerReduceStringIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *integerReduceStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// integerReduceStringPoint stores the reduced data for a name/tag combination.
type integerReduceStringPoint struct {
	Name       string
	Tags       Tags
	Aggregator IntegerPointAggregator
	Emitter    StringPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *integerReduceStringIterator) reduce() ([]StringPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*integerReduceStringPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]StringPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(stringPointsByTime(a)))
	}
	return a, nil
}

// integerStreamStringIterator streams inputs into the iterator and emits points gradually.
type integerStreamStringIterator struct {
	input  *bufIntegerIterator
	create func() (IntegerPointAggregator, StringPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*integerReduceStringPoint
	points []StringPoint
}

// newIntegerStreamStringIterator returns a new instance of integerStreamStringIterator.
func newIntegerStreamStringIterator(input IntegerIterator, createFn func() (IntegerPointAggregator, StringPointEmitter), opt IteratorOptions) *integerStreamStringIterator {
	return &integerStreamStringIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*integerReduceStringPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerStreamStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerStreamStringIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *integerStreamStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *integerStreamStringIterator) reduce() ([]StringPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []StringPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// integerReduceBooleanIterator executes a reducer for every interval and buffers the result.
type integerReduceBooleanIterator struct {
	input    *bufIntegerIterator
	create   func() (IntegerPointAggregator, BooleanPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []BooleanPoint
	keepTags bool
}

func newIntegerReduceBooleanIterator(input IntegerIterator, opt IteratorOptions, createFn func() (IntegerPointAggregator, BooleanPointEmitter)) *integerReduceBooleanIterator {
	return &integerReduceBooleanIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *integerReduceBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerReduceBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *integerReduceBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// integerReduceBooleanPoint stores the reduced data for a name/tag combination.
type integerReduceBooleanPoint struct {
	Name       string
	Tags       Tags
	Aggregator IntegerPointAggregator
	Emitter    BooleanPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *integerReduceBooleanIterator) reduce() ([]BooleanPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*integerReduceBooleanPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]BooleanPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(booleanPointsByTime(a)))
	}
	return a, nil
}

// integerStreamBooleanIterator streams inputs into the iterator and emits points gradually.
type integerStreamBooleanIterator struct {
	input  *bufIntegerIterator
	create func() (IntegerPointAggregator, BooleanPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*integerReduceBooleanPoint
	points []BooleanPoint
}

// newIntegerStreamBooleanIterator returns a new instance of integerStreamBooleanIterator.
func newIntegerStreamBooleanIterator(input IntegerIterator, createFn func() (IntegerPointAggregator, BooleanPointEmitter), opt IteratorOptions) *integerStreamBooleanIterator {
	return &integerStreamBooleanIterator{
		input:  newBufIntegerIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*integerReduceBooleanPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerStreamBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerStreamBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *integerStreamBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *integerStreamBooleanIterator) reduce() ([]BooleanPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []BooleanPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &integerReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateInteger(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// integerDedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type integerDedupeIterator struct {
	input IntegerIterator
	m     map[string]struct{} // lookup of points already sent
}

type integerIteratorMapper struct {
	cur    Cursor
	row    Row
	driver IteratorMap   // which iterator to use for the primary value, can be nil
	fields []IteratorMap // which iterator to use for an aux field
	point  IntegerPoint
}

func newIntegerIteratorMapper(cur Cursor, driver IteratorMap, fields []IteratorMap, opt IteratorOptions) *integerIteratorMapper {
	return &integerIteratorMapper{
		cur:    cur,
		driver: driver,
		fields: fields,
		point: IntegerPoint{
			Aux: make([]interface{}, len(fields)),
		},
	}
}

func (itr *integerIteratorMapper) Next() (*IntegerPoint, error) {
	if !itr.cur.Scan(&itr.row) {
		if err := itr.cur.Err(); err != nil {
			return nil, err
		}
		return nil, nil
	}

	itr.point.Time = itr.row.Time
	itr.point.Name = itr.row.Series.Name
	itr.point.Tags = itr.row.Series.Tags

	if itr.driver != nil {
		if v := itr.driver.Value(&itr.row); v != nil {
			if v, ok := castToInteger(v); ok {
				itr.point.Value = v
				itr.point.Nil = false
			} else {
				itr.point.Value = 0
				itr.point.Nil = true
			}
		} else {
			itr.point.Value = 0
			itr.point.Nil = true
		}
	}
	for i, f := range itr.fields {
		itr.point.Aux[i] = f.Value(&itr.row)
	}
	return &itr.point, nil
}

func (itr *integerIteratorMapper) Stats() IteratorStats {
	return itr.cur.Stats()
}

func (itr *integerIteratorMapper) Close() error {
	return itr.cur.Close()
}

type integerFilterIterator struct {
	input IntegerIterator
	cond  influxql.Expr
	opt   IteratorOptions
	m     map[string]interface{}
}

func newIntegerFilterIterator(input IntegerIterator, cond influxql.Expr, opt IteratorOptions) IntegerIterator {
	// Strip out time conditions from the WHERE clause.
	// TODO(jsternberg): This should really be done for us when creating the IteratorOptions struct.
	n := influxql.RewriteFunc(influxql.CloneExpr(cond), func(n influxql.Node) influxql.Node {
		switch n := n.(type) {
		case *influxql.BinaryExpr:
			if n.LHS.String() == "time" {
				return &influxql.BooleanLiteral{Val: true}
			}
		}
		return n
	})

	cond, _ = n.(influxql.Expr)
	if cond == nil {
		return input
	} else if n, ok := cond.(*influxql.BooleanLiteral); ok && n.Val {
		return input
	}

	return &integerFilterIterator{
		input: input,
		cond:  cond,
		opt:   opt,
		m:     make(map[string]interface{}),
	}
}

func (itr *integerFilterIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *integerFilterIterator) Close() error         { return itr.input.Close() }

func (itr *integerFilterIterator) Next() (*IntegerPoint, error) {
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		}

		for i, ref := range itr.opt.Aux {
			itr.m[ref.Val] = p.Aux[i]
		}
		for k, v := range p.Tags.KeyValues() {
			itr.m[k] = v
		}

		if !influxql.EvalBool(itr.cond, itr.m) {
			continue
		}
		return p, nil
	}
}

type integerTagSubsetIterator struct {
	input      IntegerIterator
	point      IntegerPoint
	lastTags   Tags
	dimensions []string
}

func newIntegerTagSubsetIterator(input IntegerIterator, opt IteratorOptions) *integerTagSubsetIterator {
	return &integerTagSubsetIterator{
		input:      input,
		dimensions: opt.GetDimensions(),
	}
}

func (itr *integerTagSubsetIterator) Next() (*IntegerPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p == nil {
		return nil, nil
	}

	itr.point.Name = p.Name
	if !p.Tags.Equal(itr.lastTags) {
		itr.point.Tags = p.Tags.Subset(itr.dimensions)
		itr.lastTags = p.Tags
	}
	itr.point.Time = p.Time
	itr.point.Value = p.Value
	itr.point.Aux = p.Aux
	itr.point.Aggregated = p.Aggregated
	itr.point.Nil = p.Nil
	return &itr.point, nil
}

func (itr *integerTagSubsetIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *integerTagSubsetIterator) Close() error {
	return itr.input.Close()
}

// newIntegerDedupeIterator returns a new instance of integerDedupeIterator.
func newIntegerDedupeIterator(input IntegerIterator) *integerDedupeIterator {
	return &integerDedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *integerDedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *integerDedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *integerDedupeIterator) Next() (*IntegerPoint, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encodeIntegerPoint(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// integerReaderIterator represents an iterator that streams from a reader.
type integerReaderIterator struct {
	r   io.Reader
	dec *IntegerPointDecoder
}

// newIntegerReaderIterator returns a new instance of integerReaderIterator.
func newIntegerReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *integerReaderIterator {
	dec := NewIntegerPointDecoder(ctx, r)
	dec.stats = stats

	return &integerReaderIterator{
		r:   r,
		dec: dec,
	}
}

// Stats returns stats about points processed.
func (itr *integerReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *integerReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *integerReaderIterator) Next() (*IntegerPoint, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &IntegerPoint{}
	if err := itr.dec.DecodeIntegerPoint(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}

// UnsignedIterator represents a stream of unsigned points.
type UnsignedIterator interface {
	Iterator
	Next() (*UnsignedPoint, error)
}

// newUnsignedIterators converts a slice of Iterator to a slice of UnsignedIterator.
// Drop and closes any iterator in itrs that is not a UnsignedIterator and cannot
// be cast to a UnsignedIterator.
func newUnsignedIterators(itrs []Iterator) []UnsignedIterator {
	a := make([]UnsignedIterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case UnsignedIterator:
			a = append(a, itr)
		default:
			itr.Close()
		}
	}
	return a
}

// bufUnsignedIterator represents a buffered UnsignedIterator.
type bufUnsignedIterator struct {
	itr UnsignedIterator
	buf *UnsignedPoint
}

// newBufUnsignedIterator returns a buffered UnsignedIterator.
func newBufUnsignedIterator(itr UnsignedIterator) *bufUnsignedIterator {
	return &bufUnsignedIterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *bufUnsignedIterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *bufUnsignedIterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *bufUnsignedIterator) peek() (*UnsignedPoint, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *bufUnsignedIterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *bufUnsignedIterator) Next() (*UnsignedPoint, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *bufUnsignedIterator) NextInWindow(startTime, endTime int64) (*UnsignedPoint, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *bufUnsignedIterator) unread(v *UnsignedPoint) { itr.buf = v }

// unsignedMergeIterator represents an iterator that combines multiple unsigned iterators.
type unsignedMergeIterator struct {
	inputs []UnsignedIterator
	heap   *unsignedMergeHeap
	init   bool

	closed bool
	mu     sync.RWMutex

	// Current iterator and window.
	curr   *unsignedMergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// newUnsignedMergeIterator returns a new instance of unsignedMergeIterator.
func newUnsignedMergeIterator(inputs []UnsignedIterator, opt IteratorOptions) *unsignedMergeIterator {
	itr := &unsignedMergeIterator{
		inputs: inputs,
		heap: &unsignedMergeHeap{
			items: make([]*unsignedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBufUnsignedIterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &unsignedMergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *unsignedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *unsignedMergeIterator) Close() error {
	itr.mu.Lock()
	defer itr.mu.Unlock()

	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	itr.closed = true
	return nil
}

// Next returns the next point from the iterator.
func (itr *unsignedMergeIterator) Next() (*UnsignedPoint, error) {
	itr.mu.RLock()
	defer itr.mu.RUnlock()
	if itr.closed {
		return nil, nil
	}

	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*unsignedMergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*unsignedMergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			tags := p.Tags.Subset(itr.heap.opt.Dimensions)
			itr.window.name, itr.window.tags = p.Name, tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if tags := p.Tags.Subset(itr.heap.opt.Dimensions); window.tags != tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// unsignedMergeHeap represents a heap of unsignedMergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type unsignedMergeHeap struct {
	opt   IteratorOptions
	items []*unsignedMergeHeapItem
}

func (h *unsignedMergeHeap) Len() int      { return len(h.items) }
func (h *unsignedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *unsignedMergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() < yTags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() > yTags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}

func (h *unsignedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*unsignedMergeHeapItem))
}

func (h *unsignedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type unsignedMergeHeapItem struct {
	itr *bufUnsignedIterator
}

// unsignedSortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type unsignedSortedMergeIterator struct {
	inputs []UnsignedIterator
	heap   *unsignedSortedMergeHeap
	init   bool
}

// newUnsignedSortedMergeIterator returns an instance of unsignedSortedMergeIterator.
func newUnsignedSortedMergeIterator(inputs []UnsignedIterator, opt IteratorOptions) Iterator {
	itr := &unsignedSortedMergeIterator{
		inputs: inputs,
		heap: &unsignedSortedMergeHeap{
			items: make([]*unsignedSortedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &unsignedSortedMergeHeapItem{itr: input})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *unsignedSortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *unsignedSortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *unsignedSortedMergeIterator) Next() (*UnsignedPoint, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *unsignedSortedMergeIterator) pop() (*UnsignedPoint, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*unsignedSortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	if len(itr.heap.items) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(itr.heap).(*unsignedSortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(itr.heap, item)
	}

	return p, nil
}

// unsignedSortedMergeHeap represents a heap of unsignedSortedMergeHeapItems.
// Items are sorted with the following priority:
//     - By their measurement name;
//     - By their tag keys/values;
//     - By time; or
//     - By their Aux field values.
//
type unsignedSortedMergeHeap struct {
	opt   IteratorOptions
	items []*unsignedSortedMergeHeapItem
}

func (h *unsignedSortedMergeHeap) Len() int      { return len(h.items) }
func (h *unsignedSortedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *unsignedSortedMergeHeap) Less(i, j int) bool {
	x, y := h.items[i].point, h.items[j].point

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
			return xTags.ID() < yTags.ID()
		}

		if x.Time != y.Time {
			return x.Time < y.Time
		}

		if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
			for i := 0; i < len(x.Aux); i++ {
				v1, ok1 := x.Aux[i].(string)
				v2, ok2 := y.Aux[i].(string)
				if !ok1 || !ok2 {
					// Unsupported types used in Aux fields. Maybe they
					// need to be added here?
					return false
				} else if v1 == v2 {
					continue
				}
				return v1 < v2
			}
		}
		return false // Times and/or Aux fields are equal.
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
		return xTags.ID() > yTags.ID()
	}

	if x.Time != y.Time {
		return x.Time > y.Time
	}

	if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
		for i := 0; i < len(x.Aux); i++ {
			v1, ok1 := x.Aux[i].(string)
			v2, ok2 := y.Aux[i].(string)
			if !ok1 || !ok2 {
				// Unsupported types used in Aux fields. Maybe they
				// need to be added here?
				return false
			} else if v1 == v2 {
				continue
			}
			return v1 > v2
		}
	}
	return false // Times and/or Aux fields are equal.
}

func (h *unsignedSortedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*unsignedSortedMergeHeapItem))
}

func (h *unsignedSortedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type unsignedSortedMergeHeapItem struct {
	point *UnsignedPoint
	err   error
	itr   UnsignedIterator
}

// unsignedIteratorScanner scans the results of a UnsignedIterator into a map.
type unsignedIteratorScanner struct {
	input        *bufUnsignedIterator
	err          error
	keys         []influxql.VarRef
	defaultValue interface{}
}

// newUnsignedIteratorScanner creates a new IteratorScanner.
func newUnsignedIteratorScanner(input UnsignedIterator, keys []influxql.VarRef, defaultValue interface{}) *unsignedIteratorScanner {
	return &unsignedIteratorScanner{
		input:        newBufUnsignedIterator(input),
		keys:         keys,
		defaultValue: defaultValue,
	}
}

func (s *unsignedIteratorScanner) Peek() (int64, string, Tags) {
	if s.err != nil {
		return ZeroTime, "", Tags{}
	}

	p, err := s.input.peek()
	if err != nil {
		s.err = err
		return ZeroTime, "", Tags{}
	} else if p == nil {
		return ZeroTime, "", Tags{}
	}
	return p.Time, p.Name, p.Tags
}

func (s *unsignedIteratorScanner) ScanAt(ts int64, name string, tags Tags, m map[string]interface{}) {
	if s.err != nil {
		return
	}

	p, err := s.input.Next()
	if err != nil {
		s.err = err
		return
	} else if p == nil {
		s.useDefaults(m)
		return
	} else if p.Time != ts || p.Name != name || !p.Tags.Equals(&tags) {
		s.useDefaults(m)
		s.input.unread(p)
		return
	}

	if k := s.keys[0]; k.Val != "" {
		if p.Nil {
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		} else {
			m[k.Val] = p.Value
		}
	}
	for i, v := range p.Aux {
		k := s.keys[i+1]
		switch v.(type) {
		case float64, int64, uint64, string, bool:
			m[k.Val] = v
		default:
			// Insert the fill value if one was specified.
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		}
	}
}

func (s *unsignedIteratorScanner) useDefaults(m map[string]interface{}) {
	if s.defaultValue == SkipDefault {
		return
	}
	for _, k := range s.keys {
		if k.Val == "" {
			continue
		}
		m[k.Val] = castToType(s.defaultValue, k.Type)
	}
}

func (s *unsignedIteratorScanner) Stats() IteratorStats { return s.input.Stats() }
func (s *unsignedIteratorScanner) Err() error           { return s.err }
func (s *unsignedIteratorScanner) Close() error         { return s.input.Close() }

// unsignedParallelIterator represents an iterator that pulls data in a separate goroutine.
type unsignedParallelIterator struct {
	input UnsignedIterator
	ch    chan unsignedPointError

	once    sync.Once
	closing chan struct{}
	wg      sync.WaitGroup
}

// newUnsignedParallelIterator returns a new instance of unsignedParallelIterator.
func newUnsignedParallelIterator(input UnsignedIterator) *unsignedParallelIterator {
	itr := &unsignedParallelIterator{
		input:   input,
		ch:      make(chan unsignedPointError, 256),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *unsignedParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *unsignedParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *unsignedParallelIterator) Next() (*UnsignedPoint, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *unsignedParallelIterator) monitor() {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()
		if p != nil {
			p = p.Clone()
		}

		select {
		case <-itr.closing:
			return
		case itr.ch <- unsignedPointError{point: p, err: err}:
		}
	}
}

type unsignedPointError struct {
	point *UnsignedPoint
	err   error
}

// unsignedLimitIterator represents an iterator that limits points per group.
type unsignedLimitIterator struct {
	input UnsignedIterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// newUnsignedLimitIterator returns a new instance of unsignedLimitIterator.
func newUnsignedLimitIterator(input UnsignedIterator, opt IteratorOptions) *unsignedLimitIterator {
	return &unsignedLimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *unsignedLimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *unsignedLimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *unsignedLimitIterator) Next() (*UnsignedPoint, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			continue
		}

		return p, nil
	}
}

type unsignedFillIterator struct {
	input     *bufUnsignedIterator
	prev      UnsignedPoint
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name   string
		tags   Tags
		time   int64
		offset int64
	}
}

func newUnsignedFillIterator(input UnsignedIterator, expr influxql.Expr, opt IteratorOptions) *unsignedFillIterator {
	if opt.Fill == influxql.NullFill {
		if expr, ok := expr.(*influxql.Call); ok && expr.Name == "count" {
			opt.Fill = influxql.NumberFill
			opt.FillValue = uint64(0)
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &unsignedFillIterator{
		input:     newBufUnsignedIterator(input),
		prev:      UnsignedPoint{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *unsignedFillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *unsignedFillIterator) Close() error         { return itr.input.Close() }

func (itr *unsignedFillIterator) Next() (*UnsignedPoint, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.startTime == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	if p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending && itr.window.time <= itr.endTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		} else if !itr.opt.Ascending && itr.window.time >= itr.endTime && itr.endTime != influxql.MinTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.window.time == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.prev = UnsignedPoint{Nil: true}
	}

	// Check if the point is our next expected point.
CONSTRUCT:
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &UnsignedPoint{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case influxql.LinearFill:
			if !itr.prev.Nil {
				next, err := itr.input.peek()
				if err != nil {
					return nil, err
				} else if next != nil && next.Name == itr.window.name && next.Tags.ID() == itr.window.tags.ID() {
					interval := int64(itr.opt.Interval.Duration)
					start := itr.window.time / interval
					p.Value = linearUnsigned(start, itr.prev.Time/interval, next.Time/interval, itr.prev.Value, next.Value)
				} else {
					p.Nil = true
				}
			} else {
				p.Nil = true
			}

		case influxql.NullFill:
			p.Nil = true
		case influxql.NumberFill:
			p.Value, _ = castToUnsigned(itr.opt.FillValue)
		case influxql.PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time += int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time -= int64(itr.opt.Interval.Duration)
	}

	// Check to see if we have passed over an offset change and adjust the time
	// to account for this new offset.
	if itr.opt.Location != nil {
		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
			diff := itr.window.offset - offset
			if abs(diff) < int64(itr.opt.Interval.Duration) {
				itr.window.time += diff
			}
			itr.window.offset = offset
		}
	}
	return p, nil
}

// unsignedIntervalIterator represents a unsigned implementation of IntervalIterator.
type unsignedIntervalIterator struct {
	input UnsignedIterator
	opt   IteratorOptions
}

func newUnsignedIntervalIterator(input UnsignedIterator, opt IteratorOptions) *unsignedIntervalIterator {
	return &unsignedIntervalIterator{input: input, opt: opt}
}

func (itr *unsignedIntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *unsignedIntervalIterator) Close() error         { return itr.input.Close() }

func (itr *unsignedIntervalIterator) Next() (*UnsignedPoint, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	// If we see the minimum allowable time, set the time to zero so we don't
	// break the default returned time for aggregate queries without times.
	if p.Time == influxql.MinTime {
		p.Time = 0
	}
	return p, nil
}

// unsignedInterruptIterator represents a unsigned implementation of InterruptIterator.
type unsignedInterruptIterator struct {
	input   UnsignedIterator
	closing <-chan struct{}
	count   int
}

func newUnsignedInterruptIterator(input UnsignedIterator, closing <-chan struct{}) *unsignedInterruptIterator {
	return &unsignedInterruptIterator{input: input, closing: closing}
}

func (itr *unsignedInterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *unsignedInterruptIterator) Close() error         { return itr.input.Close() }

func (itr *unsignedInterruptIterator) Next() (*UnsignedPoint, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count&0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, itr.Close()
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// unsignedCloseInterruptIterator represents a unsigned implementation of CloseInterruptIterator.
type unsignedCloseInterruptIterator struct {
	input   UnsignedIterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func newUnsignedCloseInterruptIterator(input UnsignedIterator, closing <-chan struct{}) *unsignedCloseInterruptIterator {
	itr := &unsignedCloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *unsignedCloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *unsignedCloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *unsignedCloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *unsignedCloseInterruptIterator) Next() (*UnsignedPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// unsignedReduceFloatIterator executes a reducer for every interval and buffers the result.
type unsignedReduceFloatIterator struct {
	input    *bufUnsignedIterator
	create   func() (UnsignedPointAggregator, FloatPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []FloatPoint
	keepTags bool
}

func newUnsignedReduceFloatIterator(input UnsignedIterator, opt IteratorOptions, createFn func() (UnsignedPointAggregator, FloatPointEmitter)) *unsignedReduceFloatIterator {
	return &unsignedReduceFloatIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedReduceFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedReduceFloatIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *unsignedReduceFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// unsignedReduceFloatPoint stores the reduced data for a name/tag combination.
type unsignedReduceFloatPoint struct {
	Name       string
	Tags       Tags
	Aggregator UnsignedPointAggregator
	Emitter    FloatPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *unsignedReduceFloatIterator) reduce() ([]FloatPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*unsignedReduceFloatPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]FloatPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(floatPointsByTime(a)))
	}
	return a, nil
}

// unsignedStreamFloatIterator streams inputs into the iterator and emits points gradually.
type unsignedStreamFloatIterator struct {
	input  *bufUnsignedIterator
	create func() (UnsignedPointAggregator, FloatPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*unsignedReduceFloatPoint
	points []FloatPoint
}

// newUnsignedStreamFloatIterator returns a new instance of unsignedStreamFloatIterator.
func newUnsignedStreamFloatIterator(input UnsignedIterator, createFn func() (UnsignedPointAggregator, FloatPointEmitter), opt IteratorOptions) *unsignedStreamFloatIterator {
	return &unsignedStreamFloatIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*unsignedReduceFloatPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedStreamFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedStreamFloatIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *unsignedStreamFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *unsignedStreamFloatIterator) reduce() ([]FloatPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []FloatPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// unsignedReduceIntegerIterator executes a reducer for every interval and buffers the result.
type unsignedReduceIntegerIterator struct {
	input    *bufUnsignedIterator
	create   func() (UnsignedPointAggregator, IntegerPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []IntegerPoint
	keepTags bool
}

func newUnsignedReduceIntegerIterator(input UnsignedIterator, opt IteratorOptions, createFn func() (UnsignedPointAggregator, IntegerPointEmitter)) *unsignedReduceIntegerIterator {
	return &unsignedReduceIntegerIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedReduceIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedReduceIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *unsignedReduceIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// unsignedReduceIntegerPoint stores the reduced data for a name/tag combination.
type unsignedReduceIntegerPoint struct {
	Name       string
	Tags       Tags
	Aggregator UnsignedPointAggregator
	Emitter    IntegerPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *unsignedReduceIntegerIterator) reduce() ([]IntegerPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*unsignedReduceIntegerPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]IntegerPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(integerPointsByTime(a)))
	}
	return a, nil
}

// unsignedStreamIntegerIterator streams inputs into the iterator and emits points gradually.
type unsignedStreamIntegerIterator struct {
	input  *bufUnsignedIterator
	create func() (UnsignedPointAggregator, IntegerPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*unsignedReduceIntegerPoint
	points []IntegerPoint
}

// newUnsignedStreamIntegerIterator returns a new instance of unsignedStreamIntegerIterator.
func newUnsignedStreamIntegerIterator(input UnsignedIterator, createFn func() (UnsignedPointAggregator, IntegerPointEmitter), opt IteratorOptions) *unsignedStreamIntegerIterator {
	return &unsignedStreamIntegerIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*unsignedReduceIntegerPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedStreamIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedStreamIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *unsignedStreamIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *unsignedStreamIntegerIterator) reduce() ([]IntegerPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []IntegerPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// unsignedReduceUnsignedIterator executes a reducer for every interval and buffers the result.
type unsignedReduceUnsignedIterator struct {
	input    *bufUnsignedIterator
	create   func() (UnsignedPointAggregator, UnsignedPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []UnsignedPoint
	keepTags bool
}

func newUnsignedReduceUnsignedIterator(input UnsignedIterator, opt IteratorOptions, createFn func() (UnsignedPointAggregator, UnsignedPointEmitter)) *unsignedReduceUnsignedIterator {
	return &unsignedReduceUnsignedIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedReduceUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedReduceUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *unsignedReduceUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// unsignedReduceUnsignedPoint stores the reduced data for a name/tag combination.
type unsignedReduceUnsignedPoint struct {
	Name       string
	Tags       Tags
	Aggregator UnsignedPointAggregator
	Emitter    UnsignedPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *unsignedReduceUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*unsignedReduceUnsignedPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]UnsignedPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(unsignedPointsByTime(a)))
	}
	return a, nil
}

// unsignedStreamUnsignedIterator streams inputs into the iterator and emits points gradually.
type unsignedStreamUnsignedIterator struct {
	input  *bufUnsignedIterator
	create func() (UnsignedPointAggregator, UnsignedPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*unsignedReduceUnsignedPoint
	points []UnsignedPoint
}

// newUnsignedStreamUnsignedIterator returns a new instance of unsignedStreamUnsignedIterator.
func newUnsignedStreamUnsignedIterator(input UnsignedIterator, createFn func() (UnsignedPointAggregator, UnsignedPointEmitter), opt IteratorOptions) *unsignedStreamUnsignedIterator {
	return &unsignedStreamUnsignedIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*unsignedReduceUnsignedPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedStreamUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedStreamUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *unsignedStreamUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *unsignedStreamUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []UnsignedPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// unsignedReduceStringIterator executes a reducer for every interval and buffers the result.
type unsignedReduceStringIterator struct {
	input    *bufUnsignedIterator
	create   func() (UnsignedPointAggregator, StringPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []StringPoint
	keepTags bool
}

func newUnsignedReduceStringIterator(input UnsignedIterator, opt IteratorOptions, createFn func() (UnsignedPointAggregator, StringPointEmitter)) *unsignedReduceStringIterator {
	return &unsignedReduceStringIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedReduceStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedReduceStringIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *unsignedReduceStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// unsignedReduceStringPoint stores the reduced data for a name/tag combination.
type unsignedReduceStringPoint struct {
	Name       string
	Tags       Tags
	Aggregator UnsignedPointAggregator
	Emitter    StringPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *unsignedReduceStringIterator) reduce() ([]StringPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*unsignedReduceStringPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]StringPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(stringPointsByTime(a)))
	}
	return a, nil
}

// unsignedStreamStringIterator streams inputs into the iterator and emits points gradually.
type unsignedStreamStringIterator struct {
	input  *bufUnsignedIterator
	create func() (UnsignedPointAggregator, StringPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*unsignedReduceStringPoint
	points []StringPoint
}

// newUnsignedStreamStringIterator returns a new instance of unsignedStreamStringIterator.
func newUnsignedStreamStringIterator(input UnsignedIterator, createFn func() (UnsignedPointAggregator, StringPointEmitter), opt IteratorOptions) *unsignedStreamStringIterator {
	return &unsignedStreamStringIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*unsignedReduceStringPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedStreamStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedStreamStringIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *unsignedStreamStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *unsignedStreamStringIterator) reduce() ([]StringPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []StringPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// unsignedReduceBooleanIterator executes a reducer for every interval and buffers the result.
type unsignedReduceBooleanIterator struct {
	input    *bufUnsignedIterator
	create   func() (UnsignedPointAggregator, BooleanPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []BooleanPoint
	keepTags bool
}

func newUnsignedReduceBooleanIterator(input UnsignedIterator, opt IteratorOptions, createFn func() (UnsignedPointAggregator, BooleanPointEmitter)) *unsignedReduceBooleanIterator {
	return &unsignedReduceBooleanIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedReduceBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedReduceBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *unsignedReduceBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// unsignedReduceBooleanPoint stores the reduced data for a name/tag combination.
type unsignedReduceBooleanPoint struct {
	Name       string
	Tags       Tags
	Aggregator UnsignedPointAggregator
	Emitter    BooleanPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *unsignedReduceBooleanIterator) reduce() ([]BooleanPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*unsignedReduceBooleanPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]BooleanPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(booleanPointsByTime(a)))
	}
	return a, nil
}

// unsignedStreamBooleanIterator streams inputs into the iterator and emits points gradually.
type unsignedStreamBooleanIterator struct {
	input  *bufUnsignedIterator
	create func() (UnsignedPointAggregator, BooleanPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*unsignedReduceBooleanPoint
	points []BooleanPoint
}

// newUnsignedStreamBooleanIterator returns a new instance of unsignedStreamBooleanIterator.
func newUnsignedStreamBooleanIterator(input UnsignedIterator, createFn func() (UnsignedPointAggregator, BooleanPointEmitter), opt IteratorOptions) *unsignedStreamBooleanIterator {
	return &unsignedStreamBooleanIterator{
		input:  newBufUnsignedIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*unsignedReduceBooleanPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedStreamBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedStreamBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *unsignedStreamBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *unsignedStreamBooleanIterator) reduce() ([]BooleanPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []BooleanPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &unsignedReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateUnsigned(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// unsignedDedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type unsignedDedupeIterator struct {
	input UnsignedIterator
	m     map[string]struct{} // lookup of points already sent
}

type unsignedIteratorMapper struct {
	cur    Cursor
	row    Row
	driver IteratorMap   // which iterator to use for the primary value, can be nil
	fields []IteratorMap // which iterator to use for an aux field
	point  UnsignedPoint
}

func newUnsignedIteratorMapper(cur Cursor, driver IteratorMap, fields []IteratorMap, opt IteratorOptions) *unsignedIteratorMapper {
	return &unsignedIteratorMapper{
		cur:    cur,
		driver: driver,
		fields: fields,
		point: UnsignedPoint{
			Aux: make([]interface{}, len(fields)),
		},
	}
}

func (itr *unsignedIteratorMapper) Next() (*UnsignedPoint, error) {
	if !itr.cur.Scan(&itr.row) {
		if err := itr.cur.Err(); err != nil {
			return nil, err
		}
		return nil, nil
	}

	itr.point.Time = itr.row.Time
	itr.point.Name = itr.row.Series.Name
	itr.point.Tags = itr.row.Series.Tags

	if itr.driver != nil {
		if v := itr.driver.Value(&itr.row); v != nil {
			if v, ok := castToUnsigned(v); ok {
				itr.point.Value = v
				itr.point.Nil = false
			} else {
				itr.point.Value = 0
				itr.point.Nil = true
			}
		} else {
			itr.point.Value = 0
			itr.point.Nil = true
		}
	}
	for i, f := range itr.fields {
		itr.point.Aux[i] = f.Value(&itr.row)
	}
	return &itr.point, nil
}

func (itr *unsignedIteratorMapper) Stats() IteratorStats {
	return itr.cur.Stats()
}

func (itr *unsignedIteratorMapper) Close() error {
	return itr.cur.Close()
}

type unsignedFilterIterator struct {
	input UnsignedIterator
	cond  influxql.Expr
	opt   IteratorOptions
	m     map[string]interface{}
}

func newUnsignedFilterIterator(input UnsignedIterator, cond influxql.Expr, opt IteratorOptions) UnsignedIterator {
	// Strip out time conditions from the WHERE clause.
	// TODO(jsternberg): This should really be done for us when creating the IteratorOptions struct.
	n := influxql.RewriteFunc(influxql.CloneExpr(cond), func(n influxql.Node) influxql.Node {
		switch n := n.(type) {
		case *influxql.BinaryExpr:
			if n.LHS.String() == "time" {
				return &influxql.BooleanLiteral{Val: true}
			}
		}
		return n
	})

	cond, _ = n.(influxql.Expr)
	if cond == nil {
		return input
	} else if n, ok := cond.(*influxql.BooleanLiteral); ok && n.Val {
		return input
	}

	return &unsignedFilterIterator{
		input: input,
		cond:  cond,
		opt:   opt,
		m:     make(map[string]interface{}),
	}
}

func (itr *unsignedFilterIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *unsignedFilterIterator) Close() error         { return itr.input.Close() }

func (itr *unsignedFilterIterator) Next() (*UnsignedPoint, error) {
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		}

		for i, ref := range itr.opt.Aux {
			itr.m[ref.Val] = p.Aux[i]
		}
		for k, v := range p.Tags.KeyValues() {
			itr.m[k] = v
		}

		if !influxql.EvalBool(itr.cond, itr.m) {
			continue
		}
		return p, nil
	}
}

type unsignedTagSubsetIterator struct {
	input      UnsignedIterator
	point      UnsignedPoint
	lastTags   Tags
	dimensions []string
}

func newUnsignedTagSubsetIterator(input UnsignedIterator, opt IteratorOptions) *unsignedTagSubsetIterator {
	return &unsignedTagSubsetIterator{
		input:      input,
		dimensions: opt.GetDimensions(),
	}
}

func (itr *unsignedTagSubsetIterator) Next() (*UnsignedPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p == nil {
		return nil, nil
	}

	itr.point.Name = p.Name
	if !p.Tags.Equal(itr.lastTags) {
		itr.point.Tags = p.Tags.Subset(itr.dimensions)
		itr.lastTags = p.Tags
	}
	itr.point.Time = p.Time
	itr.point.Value = p.Value
	itr.point.Aux = p.Aux
	itr.point.Aggregated = p.Aggregated
	itr.point.Nil = p.Nil
	return &itr.point, nil
}

func (itr *unsignedTagSubsetIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *unsignedTagSubsetIterator) Close() error {
	return itr.input.Close()
}

// newUnsignedDedupeIterator returns a new instance of unsignedDedupeIterator.
func newUnsignedDedupeIterator(input UnsignedIterator) *unsignedDedupeIterator {
	return &unsignedDedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *unsignedDedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *unsignedDedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *unsignedDedupeIterator) Next() (*UnsignedPoint, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encodeUnsignedPoint(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// unsignedReaderIterator represents an iterator that streams from a reader.
type unsignedReaderIterator struct {
	r   io.Reader
	dec *UnsignedPointDecoder
}

// newUnsignedReaderIterator returns a new instance of unsignedReaderIterator.
func newUnsignedReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *unsignedReaderIterator {
	dec := NewUnsignedPointDecoder(ctx, r)
	dec.stats = stats

	return &unsignedReaderIterator{
		r:   r,
		dec: dec,
	}
}

// Stats returns stats about points processed.
func (itr *unsignedReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *unsignedReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *unsignedReaderIterator) Next() (*UnsignedPoint, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &UnsignedPoint{}
	if err := itr.dec.DecodeUnsignedPoint(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}

// StringIterator represents a stream of string points.
type StringIterator interface {
	Iterator
	Next() (*StringPoint, error)
}

// newStringIterators converts a slice of Iterator to a slice of StringIterator.
// Drop and closes any iterator in itrs that is not a StringIterator and cannot
// be cast to a StringIterator.
func newStringIterators(itrs []Iterator) []StringIterator {
	a := make([]StringIterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case StringIterator:
			a = append(a, itr)
		default:
			itr.Close()
		}
	}
	return a
}

// bufStringIterator represents a buffered StringIterator.
type bufStringIterator struct {
	itr StringIterator
	buf *StringPoint
}

// newBufStringIterator returns a buffered StringIterator.
func newBufStringIterator(itr StringIterator) *bufStringIterator {
	return &bufStringIterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *bufStringIterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *bufStringIterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *bufStringIterator) peek() (*StringPoint, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *bufStringIterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *bufStringIterator) Next() (*StringPoint, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *bufStringIterator) NextInWindow(startTime, endTime int64) (*StringPoint, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *bufStringIterator) unread(v *StringPoint) { itr.buf = v }

// stringMergeIterator represents an iterator that combines multiple string iterators.
type stringMergeIterator struct {
	inputs []StringIterator
	heap   *stringMergeHeap
	init   bool

	closed bool
	mu     sync.RWMutex

	// Current iterator and window.
	curr   *stringMergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// newStringMergeIterator returns a new instance of stringMergeIterator.
func newStringMergeIterator(inputs []StringIterator, opt IteratorOptions) *stringMergeIterator {
	itr := &stringMergeIterator{
		inputs: inputs,
		heap: &stringMergeHeap{
			items: make([]*stringMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBufStringIterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &stringMergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *stringMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *stringMergeIterator) Close() error {
	itr.mu.Lock()
	defer itr.mu.Unlock()

	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	itr.closed = true
	return nil
}

// Next returns the next point from the iterator.
func (itr *stringMergeIterator) Next() (*StringPoint, error) {
	itr.mu.RLock()
	defer itr.mu.RUnlock()
	if itr.closed {
		return nil, nil
	}

	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*stringMergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*stringMergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			tags := p.Tags.Subset(itr.heap.opt.Dimensions)
			itr.window.name, itr.window.tags = p.Name, tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if tags := p.Tags.Subset(itr.heap.opt.Dimensions); window.tags != tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// stringMergeHeap represents a heap of stringMergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type stringMergeHeap struct {
	opt   IteratorOptions
	items []*stringMergeHeapItem
}

func (h *stringMergeHeap) Len() int      { return len(h.items) }
func (h *stringMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *stringMergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() < yTags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() > yTags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}

func (h *stringMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*stringMergeHeapItem))
}

func (h *stringMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type stringMergeHeapItem struct {
	itr *bufStringIterator
}

// stringSortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type stringSortedMergeIterator struct {
	inputs []StringIterator
	heap   *stringSortedMergeHeap
	init   bool
}

// newStringSortedMergeIterator returns an instance of stringSortedMergeIterator.
func newStringSortedMergeIterator(inputs []StringIterator, opt IteratorOptions) Iterator {
	itr := &stringSortedMergeIterator{
		inputs: inputs,
		heap: &stringSortedMergeHeap{
			items: make([]*stringSortedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &stringSortedMergeHeapItem{itr: input})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *stringSortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *stringSortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *stringSortedMergeIterator) Next() (*StringPoint, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *stringSortedMergeIterator) pop() (*StringPoint, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*stringSortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	if len(itr.heap.items) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(itr.heap).(*stringSortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(itr.heap, item)
	}

	return p, nil
}

// stringSortedMergeHeap represents a heap of stringSortedMergeHeapItems.
// Items are sorted with the following priority:
//     - By their measurement name;
//     - By their tag keys/values;
//     - By time; or
//     - By their Aux field values.
//
type stringSortedMergeHeap struct {
	opt   IteratorOptions
	items []*stringSortedMergeHeapItem
}

func (h *stringSortedMergeHeap) Len() int      { return len(h.items) }
func (h *stringSortedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *stringSortedMergeHeap) Less(i, j int) bool {
	x, y := h.items[i].point, h.items[j].point

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
			return xTags.ID() < yTags.ID()
		}

		if x.Time != y.Time {
			return x.Time < y.Time
		}

		if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
			for i := 0; i < len(x.Aux); i++ {
				v1, ok1 := x.Aux[i].(string)
				v2, ok2 := y.Aux[i].(string)
				if !ok1 || !ok2 {
					// Unsupported types used in Aux fields. Maybe they
					// need to be added here?
					return false
				} else if v1 == v2 {
					continue
				}
				return v1 < v2
			}
		}
		return false // Times and/or Aux fields are equal.
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
		return xTags.ID() > yTags.ID()
	}

	if x.Time != y.Time {
		return x.Time > y.Time
	}

	if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
		for i := 0; i < len(x.Aux); i++ {
			v1, ok1 := x.Aux[i].(string)
			v2, ok2 := y.Aux[i].(string)
			if !ok1 || !ok2 {
				// Unsupported types used in Aux fields. Maybe they
				// need to be added here?
				return false
			} else if v1 == v2 {
				continue
			}
			return v1 > v2
		}
	}
	return false // Times and/or Aux fields are equal.
}

func (h *stringSortedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*stringSortedMergeHeapItem))
}

func (h *stringSortedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type stringSortedMergeHeapItem struct {
	point *StringPoint
	err   error
	itr   StringIterator
}

// stringIteratorScanner scans the results of a StringIterator into a map.
type stringIteratorScanner struct {
	input        *bufStringIterator
	err          error
	keys         []influxql.VarRef
	defaultValue interface{}
}

// newStringIteratorScanner creates a new IteratorScanner.
func newStringIteratorScanner(input StringIterator, keys []influxql.VarRef, defaultValue interface{}) *stringIteratorScanner {
	return &stringIteratorScanner{
		input:        newBufStringIterator(input),
		keys:         keys,
		defaultValue: defaultValue,
	}
}

func (s *stringIteratorScanner) Peek() (int64, string, Tags) {
	if s.err != nil {
		return ZeroTime, "", Tags{}
	}

	p, err := s.input.peek()
	if err != nil {
		s.err = err
		return ZeroTime, "", Tags{}
	} else if p == nil {
		return ZeroTime, "", Tags{}
	}
	return p.Time, p.Name, p.Tags
}

func (s *stringIteratorScanner) ScanAt(ts int64, name string, tags Tags, m map[string]interface{}) {
	if s.err != nil {
		return
	}

	p, err := s.input.Next()
	if err != nil {
		s.err = err
		return
	} else if p == nil {
		s.useDefaults(m)
		return
	} else if p.Time != ts || p.Name != name || !p.Tags.Equals(&tags) {
		s.useDefaults(m)
		s.input.unread(p)
		return
	}

	if k := s.keys[0]; k.Val != "" {
		if p.Nil {
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		} else {
			m[k.Val] = p.Value
		}
	}
	for i, v := range p.Aux {
		k := s.keys[i+1]
		switch v.(type) {
		case float64, int64, uint64, string, bool:
			m[k.Val] = v
		default:
			// Insert the fill value if one was specified.
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		}
	}
}

func (s *stringIteratorScanner) useDefaults(m map[string]interface{}) {
	if s.defaultValue == SkipDefault {
		return
	}
	for _, k := range s.keys {
		if k.Val == "" {
			continue
		}
		m[k.Val] = castToType(s.defaultValue, k.Type)
	}
}

func (s *stringIteratorScanner) Stats() IteratorStats { return s.input.Stats() }
func (s *stringIteratorScanner) Err() error           { return s.err }
func (s *stringIteratorScanner) Close() error         { return s.input.Close() }

// stringParallelIterator represents an iterator that pulls data in a separate goroutine.
type stringParallelIterator struct {
	input StringIterator
	ch    chan stringPointError

	once    sync.Once
	closing chan struct{}
	wg      sync.WaitGroup
}

// newStringParallelIterator returns a new instance of stringParallelIterator.
func newStringParallelIterator(input StringIterator) *stringParallelIterator {
	itr := &stringParallelIterator{
		input:   input,
		ch:      make(chan stringPointError, 256),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *stringParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *stringParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *stringParallelIterator) Next() (*StringPoint, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *stringParallelIterator) monitor() {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()
		if p != nil {
			p = p.Clone()
		}

		select {
		case <-itr.closing:
			return
		case itr.ch <- stringPointError{point: p, err: err}:
		}
	}
}

type stringPointError struct {
	point *StringPoint
	err   error
}

// stringLimitIterator represents an iterator that limits points per group.
type stringLimitIterator struct {
	input StringIterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// newStringLimitIterator returns a new instance of stringLimitIterator.
func newStringLimitIterator(input StringIterator, opt IteratorOptions) *stringLimitIterator {
	return &stringLimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *stringLimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *stringLimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *stringLimitIterator) Next() (*StringPoint, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			continue
		}

		return p, nil
	}
}

type stringFillIterator struct {
	input     *bufStringIterator
	prev      StringPoint
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name   string
		tags   Tags
		time   int64
		offset int64
	}
}

func newStringFillIterator(input StringIterator, expr influxql.Expr, opt IteratorOptions) *stringFillIterator {
	if opt.Fill == influxql.NullFill {
		if expr, ok := expr.(*influxql.Call); ok && expr.Name == "count" {
			opt.Fill = influxql.NumberFill
			opt.FillValue = ""
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &stringFillIterator{
		input:     newBufStringIterator(input),
		prev:      StringPoint{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *stringFillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *stringFillIterator) Close() error         { return itr.input.Close() }

func (itr *stringFillIterator) Next() (*StringPoint, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.startTime == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	if p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending && itr.window.time <= itr.endTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		} else if !itr.opt.Ascending && itr.window.time >= itr.endTime && itr.endTime != influxql.MinTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.window.time == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.prev = StringPoint{Nil: true}
	}

	// Check if the point is our next expected point.
CONSTRUCT:
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &StringPoint{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case influxql.LinearFill:
			fallthrough
		case influxql.NullFill:
			p.Nil = true
		case influxql.NumberFill:
			p.Value, _ = castToString(itr.opt.FillValue)
		case influxql.PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time += int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time -= int64(itr.opt.Interval.Duration)
	}

	// Check to see if we have passed over an offset change and adjust the time
	// to account for this new offset.
	if itr.opt.Location != nil {
		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
			diff := itr.window.offset - offset
			if abs(diff) < int64(itr.opt.Interval.Duration) {
				itr.window.time += diff
			}
			itr.window.offset = offset
		}
	}
	return p, nil
}

// stringIntervalIterator represents a string implementation of IntervalIterator.
type stringIntervalIterator struct {
	input StringIterator
	opt   IteratorOptions
}

func newStringIntervalIterator(input StringIterator, opt IteratorOptions) *stringIntervalIterator {
	return &stringIntervalIterator{input: input, opt: opt}
}

func (itr *stringIntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *stringIntervalIterator) Close() error         { return itr.input.Close() }

func (itr *stringIntervalIterator) Next() (*StringPoint, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	// If we see the minimum allowable time, set the time to zero so we don't
	// break the default returned time for aggregate queries without times.
	if p.Time == influxql.MinTime {
		p.Time = 0
	}
	return p, nil
}

// stringInterruptIterator represents a string implementation of InterruptIterator.
type stringInterruptIterator struct {
	input   StringIterator
	closing <-chan struct{}
	count   int
}

func newStringInterruptIterator(input StringIterator, closing <-chan struct{}) *stringInterruptIterator {
	return &stringInterruptIterator{input: input, closing: closing}
}

func (itr *stringInterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *stringInterruptIterator) Close() error         { return itr.input.Close() }

func (itr *stringInterruptIterator) Next() (*StringPoint, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count&0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, itr.Close()
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// stringCloseInterruptIterator represents a string implementation of CloseInterruptIterator.
type stringCloseInterruptIterator struct {
	input   StringIterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func newStringCloseInterruptIterator(input StringIterator, closing <-chan struct{}) *stringCloseInterruptIterator {
	itr := &stringCloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *stringCloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *stringCloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *stringCloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *stringCloseInterruptIterator) Next() (*StringPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// stringReduceFloatIterator executes a reducer for every interval and buffers the result.
type stringReduceFloatIterator struct {
	input    *bufStringIterator
	create   func() (StringPointAggregator, FloatPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []FloatPoint
	keepTags bool
}

func newStringReduceFloatIterator(input StringIterator, opt IteratorOptions, createFn func() (StringPointAggregator, FloatPointEmitter)) *stringReduceFloatIterator {
	return &stringReduceFloatIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *stringReduceFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringReduceFloatIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *stringReduceFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// stringReduceFloatPoint stores the reduced data for a name/tag combination.
type stringReduceFloatPoint struct {
	Name       string
	Tags       Tags
	Aggregator StringPointAggregator
	Emitter    FloatPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *stringReduceFloatIterator) reduce() ([]FloatPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*stringReduceFloatPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]FloatPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(floatPointsByTime(a)))
	}
	return a, nil
}

// stringStreamFloatIterator streams inputs into the iterator and emits points gradually.
type stringStreamFloatIterator struct {
	input  *bufStringIterator
	create func() (StringPointAggregator, FloatPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*stringReduceFloatPoint
	points []FloatPoint
}

// newStringStreamFloatIterator returns a new instance of stringStreamFloatIterator.
func newStringStreamFloatIterator(input StringIterator, createFn func() (StringPointAggregator, FloatPointEmitter), opt IteratorOptions) *stringStreamFloatIterator {
	return &stringStreamFloatIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*stringReduceFloatPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringStreamFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringStreamFloatIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *stringStreamFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *stringStreamFloatIterator) reduce() ([]FloatPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []FloatPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// stringReduceIntegerIterator executes a reducer for every interval and buffers the result.
type stringReduceIntegerIterator struct {
	input    *bufStringIterator
	create   func() (StringPointAggregator, IntegerPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []IntegerPoint
	keepTags bool
}

func newStringReduceIntegerIterator(input StringIterator, opt IteratorOptions, createFn func() (StringPointAggregator, IntegerPointEmitter)) *stringReduceIntegerIterator {
	return &stringReduceIntegerIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *stringReduceIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringReduceIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *stringReduceIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// stringReduceIntegerPoint stores the reduced data for a name/tag combination.
type stringReduceIntegerPoint struct {
	Name       string
	Tags       Tags
	Aggregator StringPointAggregator
	Emitter    IntegerPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *stringReduceIntegerIterator) reduce() ([]IntegerPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*stringReduceIntegerPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]IntegerPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(integerPointsByTime(a)))
	}
	return a, nil
}

// stringStreamIntegerIterator streams inputs into the iterator and emits points gradually.
type stringStreamIntegerIterator struct {
	input  *bufStringIterator
	create func() (StringPointAggregator, IntegerPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*stringReduceIntegerPoint
	points []IntegerPoint
}

// newStringStreamIntegerIterator returns a new instance of stringStreamIntegerIterator.
func newStringStreamIntegerIterator(input StringIterator, createFn func() (StringPointAggregator, IntegerPointEmitter), opt IteratorOptions) *stringStreamIntegerIterator {
	return &stringStreamIntegerIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*stringReduceIntegerPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringStreamIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringStreamIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *stringStreamIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *stringStreamIntegerIterator) reduce() ([]IntegerPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []IntegerPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// stringReduceUnsignedIterator executes a reducer for every interval and buffers the result.
type stringReduceUnsignedIterator struct {
	input    *bufStringIterator
	create   func() (StringPointAggregator, UnsignedPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []UnsignedPoint
	keepTags bool
}

func newStringReduceUnsignedIterator(input StringIterator, opt IteratorOptions, createFn func() (StringPointAggregator, UnsignedPointEmitter)) *stringReduceUnsignedIterator {
	return &stringReduceUnsignedIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *stringReduceUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringReduceUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *stringReduceUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// stringReduceUnsignedPoint stores the reduced data for a name/tag combination.
type stringReduceUnsignedPoint struct {
	Name       string
	Tags       Tags
	Aggregator StringPointAggregator
	Emitter    UnsignedPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *stringReduceUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*stringReduceUnsignedPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]UnsignedPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(unsignedPointsByTime(a)))
	}
	return a, nil
}

// stringStreamUnsignedIterator streams inputs into the iterator and emits points gradually.
type stringStreamUnsignedIterator struct {
	input  *bufStringIterator
	create func() (StringPointAggregator, UnsignedPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*stringReduceUnsignedPoint
	points []UnsignedPoint
}

// newStringStreamUnsignedIterator returns a new instance of stringStreamUnsignedIterator.
func newStringStreamUnsignedIterator(input StringIterator, createFn func() (StringPointAggregator, UnsignedPointEmitter), opt IteratorOptions) *stringStreamUnsignedIterator {
	return &stringStreamUnsignedIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*stringReduceUnsignedPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringStreamUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringStreamUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *stringStreamUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *stringStreamUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []UnsignedPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// stringReduceStringIterator executes a reducer for every interval and buffers the result.
type stringReduceStringIterator struct {
	input    *bufStringIterator
	create   func() (StringPointAggregator, StringPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []StringPoint
	keepTags bool
}

func newStringReduceStringIterator(input StringIterator, opt IteratorOptions, createFn func() (StringPointAggregator, StringPointEmitter)) *stringReduceStringIterator {
	return &stringReduceStringIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *stringReduceStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringReduceStringIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *stringReduceStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// stringReduceStringPoint stores the reduced data for a name/tag combination.
type stringReduceStringPoint struct {
	Name       string
	Tags       Tags
	Aggregator StringPointAggregator
	Emitter    StringPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *stringReduceStringIterator) reduce() ([]StringPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*stringReduceStringPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]StringPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(stringPointsByTime(a)))
	}
	return a, nil
}

// stringStreamStringIterator streams inputs into the iterator and emits points gradually.
type stringStreamStringIterator struct {
	input  *bufStringIterator
	create func() (StringPointAggregator, StringPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*stringReduceStringPoint
	points []StringPoint
}

// newStringStreamStringIterator returns a new instance of stringStreamStringIterator.
func newStringStreamStringIterator(input StringIterator, createFn func() (StringPointAggregator, StringPointEmitter), opt IteratorOptions) *stringStreamStringIterator {
	return &stringStreamStringIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*stringReduceStringPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringStreamStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringStreamStringIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *stringStreamStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *stringStreamStringIterator) reduce() ([]StringPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []StringPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// stringReduceBooleanIterator executes a reducer for every interval and buffers the result.
type stringReduceBooleanIterator struct {
	input    *bufStringIterator
	create   func() (StringPointAggregator, BooleanPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []BooleanPoint
	keepTags bool
}

func newStringReduceBooleanIterator(input StringIterator, opt IteratorOptions, createFn func() (StringPointAggregator, BooleanPointEmitter)) *stringReduceBooleanIterator {
	return &stringReduceBooleanIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *stringReduceBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringReduceBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *stringReduceBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// stringReduceBooleanPoint stores the reduced data for a name/tag combination.
type stringReduceBooleanPoint struct {
	Name       string
	Tags       Tags
	Aggregator StringPointAggregator
	Emitter    BooleanPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *stringReduceBooleanIterator) reduce() ([]BooleanPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*stringReduceBooleanPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]BooleanPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(booleanPointsByTime(a)))
	}
	return a, nil
}

// stringStreamBooleanIterator streams inputs into the iterator and emits points gradually.
type stringStreamBooleanIterator struct {
	input  *bufStringIterator
	create func() (StringPointAggregator, BooleanPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*stringReduceBooleanPoint
	points []BooleanPoint
}

// newStringStreamBooleanIterator returns a new instance of stringStreamBooleanIterator.
func newStringStreamBooleanIterator(input StringIterator, createFn func() (StringPointAggregator, BooleanPointEmitter), opt IteratorOptions) *stringStreamBooleanIterator {
	return &stringStreamBooleanIterator{
		input:  newBufStringIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*stringReduceBooleanPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringStreamBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringStreamBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *stringStreamBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *stringStreamBooleanIterator) reduce() ([]BooleanPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []BooleanPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &stringReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateString(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// stringDedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type stringDedupeIterator struct {
	input StringIterator
	m     map[string]struct{} // lookup of points already sent
}

type stringIteratorMapper struct {
	cur    Cursor
	row    Row
	driver IteratorMap   // which iterator to use for the primary value, can be nil
	fields []IteratorMap // which iterator to use for an aux field
	point  StringPoint
}

func newStringIteratorMapper(cur Cursor, driver IteratorMap, fields []IteratorMap, opt IteratorOptions) *stringIteratorMapper {
	return &stringIteratorMapper{
		cur:    cur,
		driver: driver,
		fields: fields,
		point: StringPoint{
			Aux: make([]interface{}, len(fields)),
		},
	}
}

func (itr *stringIteratorMapper) Next() (*StringPoint, error) {
	if !itr.cur.Scan(&itr.row) {
		if err := itr.cur.Err(); err != nil {
			return nil, err
		}
		return nil, nil
	}

	itr.point.Time = itr.row.Time
	itr.point.Name = itr.row.Series.Name
	itr.point.Tags = itr.row.Series.Tags

	if itr.driver != nil {
		if v := itr.driver.Value(&itr.row); v != nil {
			if v, ok := castToString(v); ok {
				itr.point.Value = v
				itr.point.Nil = false
			} else {
				itr.point.Value = ""
				itr.point.Nil = true
			}
		} else {
			itr.point.Value = ""
			itr.point.Nil = true
		}
	}
	for i, f := range itr.fields {
		itr.point.Aux[i] = f.Value(&itr.row)
	}
	return &itr.point, nil
}

func (itr *stringIteratorMapper) Stats() IteratorStats {
	return itr.cur.Stats()
}

func (itr *stringIteratorMapper) Close() error {
	return itr.cur.Close()
}

type stringFilterIterator struct {
	input StringIterator
	cond  influxql.Expr
	opt   IteratorOptions
	m     map[string]interface{}
}

func newStringFilterIterator(input StringIterator, cond influxql.Expr, opt IteratorOptions) StringIterator {
	// Strip out time conditions from the WHERE clause.
	// TODO(jsternberg): This should really be done for us when creating the IteratorOptions struct.
	n := influxql.RewriteFunc(influxql.CloneExpr(cond), func(n influxql.Node) influxql.Node {
		switch n := n.(type) {
		case *influxql.BinaryExpr:
			if n.LHS.String() == "time" {
				return &influxql.BooleanLiteral{Val: true}
			}
		}
		return n
	})

	cond, _ = n.(influxql.Expr)
	if cond == nil {
		return input
	} else if n, ok := cond.(*influxql.BooleanLiteral); ok && n.Val {
		return input
	}

	return &stringFilterIterator{
		input: input,
		cond:  cond,
		opt:   opt,
		m:     make(map[string]interface{}),
	}
}

func (itr *stringFilterIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *stringFilterIterator) Close() error         { return itr.input.Close() }

func (itr *stringFilterIterator) Next() (*StringPoint, error) {
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		}

		for i, ref := range itr.opt.Aux {
			itr.m[ref.Val] = p.Aux[i]
		}
		for k, v := range p.Tags.KeyValues() {
			itr.m[k] = v
		}

		if !influxql.EvalBool(itr.cond, itr.m) {
			continue
		}
		return p, nil
	}
}

type stringTagSubsetIterator struct {
	input      StringIterator
	point      StringPoint
	lastTags   Tags
	dimensions []string
}

func newStringTagSubsetIterator(input StringIterator, opt IteratorOptions) *stringTagSubsetIterator {
	return &stringTagSubsetIterator{
		input:      input,
		dimensions: opt.GetDimensions(),
	}
}

func (itr *stringTagSubsetIterator) Next() (*StringPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p == nil {
		return nil, nil
	}

	itr.point.Name = p.Name
	if !p.Tags.Equal(itr.lastTags) {
		itr.point.Tags = p.Tags.Subset(itr.dimensions)
		itr.lastTags = p.Tags
	}
	itr.point.Time = p.Time
	itr.point.Value = p.Value
	itr.point.Aux = p.Aux
	itr.point.Aggregated = p.Aggregated
	itr.point.Nil = p.Nil
	return &itr.point, nil
}

func (itr *stringTagSubsetIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *stringTagSubsetIterator) Close() error {
	return itr.input.Close()
}

// newStringDedupeIterator returns a new instance of stringDedupeIterator.
func newStringDedupeIterator(input StringIterator) *stringDedupeIterator {
	return &stringDedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *stringDedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *stringDedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *stringDedupeIterator) Next() (*StringPoint, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encodeStringPoint(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// stringReaderIterator represents an iterator that streams from a reader.
type stringReaderIterator struct {
	r   io.Reader
	dec *StringPointDecoder
}

// newStringReaderIterator returns a new instance of stringReaderIterator.
func newStringReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *stringReaderIterator {
	dec := NewStringPointDecoder(ctx, r)
	dec.stats = stats

	return &stringReaderIterator{
		r:   r,
		dec: dec,
	}
}

// Stats returns stats about points processed.
func (itr *stringReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *stringReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *stringReaderIterator) Next() (*StringPoint, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &StringPoint{}
	if err := itr.dec.DecodeStringPoint(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}

// BooleanIterator represents a stream of boolean points.
type BooleanIterator interface {
	Iterator
	Next() (*BooleanPoint, error)
}

// newBooleanIterators converts a slice of Iterator to a slice of BooleanIterator.
// Drop and closes any iterator in itrs that is not a BooleanIterator and cannot
// be cast to a BooleanIterator.
func newBooleanIterators(itrs []Iterator) []BooleanIterator {
	a := make([]BooleanIterator, 0, len(itrs))
	for _, itr := range itrs {
		switch itr := itr.(type) {
		case BooleanIterator:
			a = append(a, itr)
		default:
			itr.Close()
		}
	}
	return a
}

// bufBooleanIterator represents a buffered BooleanIterator.
type bufBooleanIterator struct {
	itr BooleanIterator
	buf *BooleanPoint
}

// newBufBooleanIterator returns a buffered BooleanIterator.
func newBufBooleanIterator(itr BooleanIterator) *bufBooleanIterator {
	return &bufBooleanIterator{itr: itr}
}

// Stats returns statistics from the input iterator.
func (itr *bufBooleanIterator) Stats() IteratorStats { return itr.itr.Stats() }

// Close closes the underlying iterator.
func (itr *bufBooleanIterator) Close() error { return itr.itr.Close() }

// peek returns the next point without removing it from the iterator.
func (itr *bufBooleanIterator) peek() (*BooleanPoint, error) {
	p, err := itr.Next()
	if err != nil {
		return nil, err
	}
	itr.unread(p)
	return p, nil
}

// peekTime returns the time of the next point.
// Returns zero time if no more points available.
func (itr *bufBooleanIterator) peekTime() (int64, error) {
	p, err := itr.peek()
	if p == nil || err != nil {
		return ZeroTime, err
	}
	return p.Time, nil
}

// Next returns the current buffer, if exists, or calls the underlying iterator.
func (itr *bufBooleanIterator) Next() (*BooleanPoint, error) {
	buf := itr.buf
	if buf != nil {
		itr.buf = nil
		return buf, nil
	}
	return itr.itr.Next()
}

// NextInWindow returns the next value if it is between [startTime, endTime).
// If the next value is outside the range then it is moved to the buffer.
func (itr *bufBooleanIterator) NextInWindow(startTime, endTime int64) (*BooleanPoint, error) {
	v, err := itr.Next()
	if v == nil || err != nil {
		return nil, err
	} else if t := v.Time; t >= endTime || t < startTime {
		itr.unread(v)
		return nil, nil
	}
	return v, nil
}

// unread sets v to the buffer. It is read on the next call to Next().
func (itr *bufBooleanIterator) unread(v *BooleanPoint) { itr.buf = v }

// booleanMergeIterator represents an iterator that combines multiple boolean iterators.
type booleanMergeIterator struct {
	inputs []BooleanIterator
	heap   *booleanMergeHeap
	init   bool

	closed bool
	mu     sync.RWMutex

	// Current iterator and window.
	curr   *booleanMergeHeapItem
	window struct {
		name      string
		tags      string
		startTime int64
		endTime   int64
	}
}

// newBooleanMergeIterator returns a new instance of booleanMergeIterator.
func newBooleanMergeIterator(inputs []BooleanIterator, opt IteratorOptions) *booleanMergeIterator {
	itr := &booleanMergeIterator{
		inputs: inputs,
		heap: &booleanMergeHeap{
			items: make([]*booleanMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Wrap in buffer, ignore any inputs without anymore points.
		bufInput := newBufBooleanIterator(input)

		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &booleanMergeHeapItem{itr: bufInput})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *booleanMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *booleanMergeIterator) Close() error {
	itr.mu.Lock()
	defer itr.mu.Unlock()

	for _, input := range itr.inputs {
		input.Close()
	}
	itr.curr = nil
	itr.inputs = nil
	itr.heap.items = nil
	itr.closed = true
	return nil
}

// Next returns the next point from the iterator.
func (itr *booleanMergeIterator) Next() (*BooleanPoint, error) {
	itr.mu.RLock()
	defer itr.mu.RUnlock()
	if itr.closed {
		return nil, nil
	}

	// Initialize the heap. This needs to be done lazily on the first call to this iterator
	// so that iterator initialization done through the Select() call returns quickly.
	// Queries can only be interrupted after the Select() call completes so any operations
	// done during iterator creation cannot be interrupted, which is why we do it here
	// instead so an interrupt can happen while initializing the heap.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*booleanMergeHeapItem, 0, len(items))
		for _, item := range items {
			if p, err := item.itr.peek(); err != nil {
				return nil, err
			} else if p == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	for {
		// Retrieve the next iterator if we don't have one.
		if itr.curr == nil {
			if len(itr.heap.items) == 0 {
				return nil, nil
			}
			itr.curr = heap.Pop(itr.heap).(*booleanMergeHeapItem)

			// Read point and set current window.
			p, err := itr.curr.itr.Next()
			if err != nil {
				return nil, err
			}
			tags := p.Tags.Subset(itr.heap.opt.Dimensions)
			itr.window.name, itr.window.tags = p.Name, tags.ID()
			itr.window.startTime, itr.window.endTime = itr.heap.opt.Window(p.Time)
			return p, nil
		}

		// Read the next point from the current iterator.
		p, err := itr.curr.itr.Next()
		if err != nil {
			return nil, err
		}

		// If there are no more points then remove iterator from heap and find next.
		if p == nil {
			itr.curr = nil
			continue
		}

		// Check if the point is inside of our current window.
		inWindow := true
		if window := itr.window; window.name != p.Name {
			inWindow = false
		} else if tags := p.Tags.Subset(itr.heap.opt.Dimensions); window.tags != tags.ID() {
			inWindow = false
		} else if opt := itr.heap.opt; opt.Ascending && p.Time >= window.endTime {
			inWindow = false
		} else if !opt.Ascending && p.Time < window.startTime {
			inWindow = false
		}

		// If it's outside our window then push iterator back on the heap and find new iterator.
		if !inWindow {
			itr.curr.itr.unread(p)
			heap.Push(itr.heap, itr.curr)
			itr.curr = nil
			continue
		}

		return p, nil
	}
}

// booleanMergeHeap represents a heap of booleanMergeHeapItems.
// Items are sorted by their next window and then by name/tags.
type booleanMergeHeap struct {
	opt   IteratorOptions
	items []*booleanMergeHeapItem
}

func (h *booleanMergeHeap) Len() int      { return len(h.items) }
func (h *booleanMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *booleanMergeHeap) Less(i, j int) bool {
	x, err := h.items[i].itr.peek()
	if err != nil {
		return true
	}
	y, err := h.items[j].itr.peek()
	if err != nil {
		return false
	}

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() < yTags.ID()
		}
	} else {
		if x.Name != y.Name {
			return x.Name > y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); xTags.ID() != yTags.ID() {
			return xTags.ID() > yTags.ID()
		}
	}

	xt, _ := h.opt.Window(x.Time)
	yt, _ := h.opt.Window(y.Time)

	if h.opt.Ascending {
		return xt < yt
	}
	return xt > yt
}

func (h *booleanMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*booleanMergeHeapItem))
}

func (h *booleanMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type booleanMergeHeapItem struct {
	itr *bufBooleanIterator
}

// booleanSortedMergeIterator is an iterator that sorts and merges multiple iterators into one.
type booleanSortedMergeIterator struct {
	inputs []BooleanIterator
	heap   *booleanSortedMergeHeap
	init   bool
}

// newBooleanSortedMergeIterator returns an instance of booleanSortedMergeIterator.
func newBooleanSortedMergeIterator(inputs []BooleanIterator, opt IteratorOptions) Iterator {
	itr := &booleanSortedMergeIterator{
		inputs: inputs,
		heap: &booleanSortedMergeHeap{
			items: make([]*booleanSortedMergeHeapItem, 0, len(inputs)),
			opt:   opt,
		},
	}

	// Initialize heap items.
	for _, input := range inputs {
		// Append to the heap.
		itr.heap.items = append(itr.heap.items, &booleanSortedMergeHeapItem{itr: input})
	}

	return itr
}

// Stats returns an aggregation of stats from the underlying iterators.
func (itr *booleanSortedMergeIterator) Stats() IteratorStats {
	var stats IteratorStats
	for _, input := range itr.inputs {
		stats.Add(input.Stats())
	}
	return stats
}

// Close closes the underlying iterators.
func (itr *booleanSortedMergeIterator) Close() error {
	for _, input := range itr.inputs {
		input.Close()
	}
	return nil
}

// Next returns the next points from the iterator.
func (itr *booleanSortedMergeIterator) Next() (*BooleanPoint, error) { return itr.pop() }

// pop returns the next point from the heap.
// Reads the next point from item's cursor and puts it back on the heap.
func (itr *booleanSortedMergeIterator) pop() (*BooleanPoint, error) {
	// Initialize the heap. See the MergeIterator to see why this has to be done lazily.
	if !itr.init {
		items := itr.heap.items
		itr.heap.items = make([]*booleanSortedMergeHeapItem, 0, len(items))
		for _, item := range items {
			var err error
			if item.point, err = item.itr.Next(); err != nil {
				return nil, err
			} else if item.point == nil {
				continue
			}
			itr.heap.items = append(itr.heap.items, item)
		}
		heap.Init(itr.heap)
		itr.init = true
	}

	if len(itr.heap.items) == 0 {
		return nil, nil
	}

	// Read the next item from the heap.
	item := heap.Pop(itr.heap).(*booleanSortedMergeHeapItem)
	if item.err != nil {
		return nil, item.err
	} else if item.point == nil {
		return nil, nil
	}

	// Copy the point for return.
	p := item.point.Clone()

	// Read the next item from the cursor. Push back to heap if one exists.
	if item.point, item.err = item.itr.Next(); item.point != nil {
		heap.Push(itr.heap, item)
	}

	return p, nil
}

// booleanSortedMergeHeap represents a heap of booleanSortedMergeHeapItems.
// Items are sorted with the following priority:
//     - By their measurement name;
//     - By their tag keys/values;
//     - By time; or
//     - By their Aux field values.
//
type booleanSortedMergeHeap struct {
	opt   IteratorOptions
	items []*booleanSortedMergeHeapItem
}

func (h *booleanSortedMergeHeap) Len() int      { return len(h.items) }
func (h *booleanSortedMergeHeap) Swap(i, j int) { h.items[i], h.items[j] = h.items[j], h.items[i] }
func (h *booleanSortedMergeHeap) Less(i, j int) bool {
	x, y := h.items[i].point, h.items[j].point

	if h.opt.Ascending {
		if x.Name != y.Name {
			return x.Name < y.Name
		} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
			return xTags.ID() < yTags.ID()
		}

		if x.Time != y.Time {
			return x.Time < y.Time
		}

		if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
			for i := 0; i < len(x.Aux); i++ {
				v1, ok1 := x.Aux[i].(string)
				v2, ok2 := y.Aux[i].(string)
				if !ok1 || !ok2 {
					// Unsupported types used in Aux fields. Maybe they
					// need to be added here?
					return false
				} else if v1 == v2 {
					continue
				}
				return v1 < v2
			}
		}
		return false // Times and/or Aux fields are equal.
	}

	if x.Name != y.Name {
		return x.Name > y.Name
	} else if xTags, yTags := x.Tags.Subset(h.opt.Dimensions), y.Tags.Subset(h.opt.Dimensions); !xTags.Equals(&yTags) {
		return xTags.ID() > yTags.ID()
	}

	if x.Time != y.Time {
		return x.Time > y.Time
	}

	if len(x.Aux) > 0 && len(x.Aux) == len(y.Aux) {
		for i := 0; i < len(x.Aux); i++ {
			v1, ok1 := x.Aux[i].(string)
			v2, ok2 := y.Aux[i].(string)
			if !ok1 || !ok2 {
				// Unsupported types used in Aux fields. Maybe they
				// need to be added here?
				return false
			} else if v1 == v2 {
				continue
			}
			return v1 > v2
		}
	}
	return false // Times and/or Aux fields are equal.
}

func (h *booleanSortedMergeHeap) Push(x interface{}) {
	h.items = append(h.items, x.(*booleanSortedMergeHeapItem))
}

func (h *booleanSortedMergeHeap) Pop() interface{} {
	old := h.items
	n := len(old)
	item := old[n-1]
	h.items = old[0 : n-1]
	return item
}

type booleanSortedMergeHeapItem struct {
	point *BooleanPoint
	err   error
	itr   BooleanIterator
}

// booleanIteratorScanner scans the results of a BooleanIterator into a map.
type booleanIteratorScanner struct {
	input        *bufBooleanIterator
	err          error
	keys         []influxql.VarRef
	defaultValue interface{}
}

// newBooleanIteratorScanner creates a new IteratorScanner.
func newBooleanIteratorScanner(input BooleanIterator, keys []influxql.VarRef, defaultValue interface{}) *booleanIteratorScanner {
	return &booleanIteratorScanner{
		input:        newBufBooleanIterator(input),
		keys:         keys,
		defaultValue: defaultValue,
	}
}

func (s *booleanIteratorScanner) Peek() (int64, string, Tags) {
	if s.err != nil {
		return ZeroTime, "", Tags{}
	}

	p, err := s.input.peek()
	if err != nil {
		s.err = err
		return ZeroTime, "", Tags{}
	} else if p == nil {
		return ZeroTime, "", Tags{}
	}
	return p.Time, p.Name, p.Tags
}

func (s *booleanIteratorScanner) ScanAt(ts int64, name string, tags Tags, m map[string]interface{}) {
	if s.err != nil {
		return
	}

	p, err := s.input.Next()
	if err != nil {
		s.err = err
		return
	} else if p == nil {
		s.useDefaults(m)
		return
	} else if p.Time != ts || p.Name != name || !p.Tags.Equals(&tags) {
		s.useDefaults(m)
		s.input.unread(p)
		return
	}

	if k := s.keys[0]; k.Val != "" {
		if p.Nil {
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		} else {
			m[k.Val] = p.Value
		}
	}
	for i, v := range p.Aux {
		k := s.keys[i+1]
		switch v.(type) {
		case float64, int64, uint64, string, bool:
			m[k.Val] = v
		default:
			// Insert the fill value if one was specified.
			if s.defaultValue != SkipDefault {
				m[k.Val] = castToType(s.defaultValue, k.Type)
			}
		}
	}
}

func (s *booleanIteratorScanner) useDefaults(m map[string]interface{}) {
	if s.defaultValue == SkipDefault {
		return
	}
	for _, k := range s.keys {
		if k.Val == "" {
			continue
		}
		m[k.Val] = castToType(s.defaultValue, k.Type)
	}
}

func (s *booleanIteratorScanner) Stats() IteratorStats { return s.input.Stats() }
func (s *booleanIteratorScanner) Err() error           { return s.err }
func (s *booleanIteratorScanner) Close() error         { return s.input.Close() }

// booleanParallelIterator represents an iterator that pulls data in a separate goroutine.
type booleanParallelIterator struct {
	input BooleanIterator
	ch    chan booleanPointError

	once    sync.Once
	closing chan struct{}
	wg      sync.WaitGroup
}

// newBooleanParallelIterator returns a new instance of booleanParallelIterator.
func newBooleanParallelIterator(input BooleanIterator) *booleanParallelIterator {
	itr := &booleanParallelIterator{
		input:   input,
		ch:      make(chan booleanPointError, 256),
		closing: make(chan struct{}),
	}
	itr.wg.Add(1)
	go itr.monitor()
	return itr
}

// Stats returns stats from the underlying iterator.
func (itr *booleanParallelIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *booleanParallelIterator) Close() error {
	itr.once.Do(func() { close(itr.closing) })
	itr.wg.Wait()
	return itr.input.Close()
}

// Next returns the next point from the iterator.
func (itr *booleanParallelIterator) Next() (*BooleanPoint, error) {
	v, ok := <-itr.ch
	if !ok {
		return nil, io.EOF
	}
	return v.point, v.err
}

// monitor runs in a separate goroutine and actively pulls the next point.
func (itr *booleanParallelIterator) monitor() {
	defer close(itr.ch)
	defer itr.wg.Done()

	for {
		// Read next point.
		p, err := itr.input.Next()
		if p != nil {
			p = p.Clone()
		}

		select {
		case <-itr.closing:
			return
		case itr.ch <- booleanPointError{point: p, err: err}:
		}
	}
}

type booleanPointError struct {
	point *BooleanPoint
	err   error
}

// booleanLimitIterator represents an iterator that limits points per group.
type booleanLimitIterator struct {
	input BooleanIterator
	opt   IteratorOptions
	n     int

	prev struct {
		name string
		tags Tags
	}
}

// newBooleanLimitIterator returns a new instance of booleanLimitIterator.
func newBooleanLimitIterator(input BooleanIterator, opt IteratorOptions) *booleanLimitIterator {
	return &booleanLimitIterator{
		input: input,
		opt:   opt,
	}
}

// Stats returns stats from the underlying iterator.
func (itr *booleanLimitIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the underlying iterators.
func (itr *booleanLimitIterator) Close() error { return itr.input.Close() }

// Next returns the next point from the iterator.
func (itr *booleanLimitIterator) Next() (*BooleanPoint, error) {
	for {
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Reset window and counter if a new window is encountered.
		if p.Name != itr.prev.name || !p.Tags.Equals(&itr.prev.tags) {
			itr.prev.name = p.Name
			itr.prev.tags = p.Tags
			itr.n = 0
		}

		// Increment counter.
		itr.n++

		// Read next point if not beyond the offset.
		if itr.n <= itr.opt.Offset {
			continue
		}

		// Read next point if we're beyond the limit.
		if itr.opt.Limit > 0 && (itr.n-itr.opt.Offset) > itr.opt.Limit {
			continue
		}

		return p, nil
	}
}

type booleanFillIterator struct {
	input     *bufBooleanIterator
	prev      BooleanPoint
	startTime int64
	endTime   int64
	auxFields []interface{}
	init      bool
	opt       IteratorOptions

	window struct {
		name   string
		tags   Tags
		time   int64
		offset int64
	}
}

func newBooleanFillIterator(input BooleanIterator, expr influxql.Expr, opt IteratorOptions) *booleanFillIterator {
	if opt.Fill == influxql.NullFill {
		if expr, ok := expr.(*influxql.Call); ok && expr.Name == "count" {
			opt.Fill = influxql.NumberFill
			opt.FillValue = false
		}
	}

	var startTime, endTime int64
	if opt.Ascending {
		startTime, _ = opt.Window(opt.StartTime)
		endTime, _ = opt.Window(opt.EndTime)
	} else {
		startTime, _ = opt.Window(opt.EndTime)
		endTime, _ = opt.Window(opt.StartTime)
	}

	var auxFields []interface{}
	if len(opt.Aux) > 0 {
		auxFields = make([]interface{}, len(opt.Aux))
	}

	return &booleanFillIterator{
		input:     newBufBooleanIterator(input),
		prev:      BooleanPoint{Nil: true},
		startTime: startTime,
		endTime:   endTime,
		auxFields: auxFields,
		opt:       opt,
	}
}

func (itr *booleanFillIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *booleanFillIterator) Close() error         { return itr.input.Close() }

func (itr *booleanFillIterator) Next() (*BooleanPoint, error) {
	if !itr.init {
		p, err := itr.input.peek()
		if p == nil || err != nil {
			return nil, err
		}
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.startTime == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.init = true
	}

	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	}

	// Check if the next point is outside of our window or is nil.
	if p == nil || p.Name != itr.window.name || p.Tags.ID() != itr.window.tags.ID() {
		// If we are inside of an interval, unread the point and continue below to
		// constructing a new point.
		if itr.opt.Ascending && itr.window.time <= itr.endTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		} else if !itr.opt.Ascending && itr.window.time >= itr.endTime && itr.endTime != influxql.MinTime {
			itr.input.unread(p)
			p = nil
			goto CONSTRUCT
		}

		// We are *not* in a current interval. If there is no next point,
		// we are at the end of all intervals.
		if p == nil {
			return nil, nil
		}

		// Set the new interval.
		itr.window.name, itr.window.tags = p.Name, p.Tags
		itr.window.time = itr.startTime
		if itr.window.time == influxql.MinTime {
			itr.window.time, _ = itr.opt.Window(p.Time)
		}
		if itr.opt.Location != nil {
			_, itr.window.offset = itr.opt.Zone(itr.window.time)
		}
		itr.prev = BooleanPoint{Nil: true}
	}

	// Check if the point is our next expected point.
CONSTRUCT:
	if p == nil || (itr.opt.Ascending && p.Time > itr.window.time) || (!itr.opt.Ascending && p.Time < itr.window.time) {
		if p != nil {
			itr.input.unread(p)
		}

		p = &BooleanPoint{
			Name: itr.window.name,
			Tags: itr.window.tags,
			Time: itr.window.time,
			Aux:  itr.auxFields,
		}

		switch itr.opt.Fill {
		case influxql.LinearFill:
			fallthrough
		case influxql.NullFill:
			p.Nil = true
		case influxql.NumberFill:
			p.Value, _ = castToBoolean(itr.opt.FillValue)
		case influxql.PreviousFill:
			if !itr.prev.Nil {
				p.Value = itr.prev.Value
				p.Nil = itr.prev.Nil
			} else {
				p.Nil = true
			}
		}
	} else {
		itr.prev = *p
	}

	// Advance the expected time. Do not advance to a new window here
	// as there may be lingering points with the same timestamp in the previous
	// window.
	if itr.opt.Ascending {
		itr.window.time += int64(itr.opt.Interval.Duration)
	} else {
		itr.window.time -= int64(itr.opt.Interval.Duration)
	}

	// Check to see if we have passed over an offset change and adjust the time
	// to account for this new offset.
	if itr.opt.Location != nil {
		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
			diff := itr.window.offset - offset
			if abs(diff) < int64(itr.opt.Interval.Duration) {
				itr.window.time += diff
			}
			itr.window.offset = offset
		}
	}
	return p, nil
}

// booleanIntervalIterator represents a boolean implementation of IntervalIterator.
type booleanIntervalIterator struct {
	input BooleanIterator
	opt   IteratorOptions
}

func newBooleanIntervalIterator(input BooleanIterator, opt IteratorOptions) *booleanIntervalIterator {
	return &booleanIntervalIterator{input: input, opt: opt}
}

func (itr *booleanIntervalIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *booleanIntervalIterator) Close() error         { return itr.input.Close() }

func (itr *booleanIntervalIterator) Next() (*BooleanPoint, error) {
	p, err := itr.input.Next()
	if p == nil || err != nil {
		return nil, err
	}
	p.Time, _ = itr.opt.Window(p.Time)
	// If we see the minimum allowable time, set the time to zero so we don't
	// break the default returned time for aggregate queries without times.
	if p.Time == influxql.MinTime {
		p.Time = 0
	}
	return p, nil
}

// booleanInterruptIterator represents a boolean implementation of InterruptIterator.
type booleanInterruptIterator struct {
	input   BooleanIterator
	closing <-chan struct{}
	count   int
}

func newBooleanInterruptIterator(input BooleanIterator, closing <-chan struct{}) *booleanInterruptIterator {
	return &booleanInterruptIterator{input: input, closing: closing}
}

func (itr *booleanInterruptIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *booleanInterruptIterator) Close() error         { return itr.input.Close() }

func (itr *booleanInterruptIterator) Next() (*BooleanPoint, error) {
	// Only check if the channel is closed every N points. This
	// intentionally checks on both 0 and N so that if the iterator
	// has been interrupted before the first point is emitted it will
	// not emit any points.
	if itr.count&0xFF == 0xFF {
		select {
		case <-itr.closing:
			return nil, itr.Close()
		default:
			// Reset iterator count to zero and fall through to emit the next point.
			itr.count = 0
		}
	}

	// Increment the counter for every point read.
	itr.count++
	return itr.input.Next()
}

// booleanCloseInterruptIterator represents a boolean implementation of CloseInterruptIterator.
type booleanCloseInterruptIterator struct {
	input   BooleanIterator
	closing <-chan struct{}
	done    chan struct{}
	once    sync.Once
}

func newBooleanCloseInterruptIterator(input BooleanIterator, closing <-chan struct{}) *booleanCloseInterruptIterator {
	itr := &booleanCloseInterruptIterator{
		input:   input,
		closing: closing,
		done:    make(chan struct{}),
	}
	go itr.monitor()
	return itr
}

func (itr *booleanCloseInterruptIterator) monitor() {
	select {
	case <-itr.closing:
		itr.Close()
	case <-itr.done:
	}
}

func (itr *booleanCloseInterruptIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *booleanCloseInterruptIterator) Close() error {
	itr.once.Do(func() {
		close(itr.done)
		itr.input.Close()
	})
	return nil
}

func (itr *booleanCloseInterruptIterator) Next() (*BooleanPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		// Check if the iterator was closed.
		select {
		case <-itr.done:
			return nil, nil
		default:
			return nil, err
		}
	}
	return p, nil
}

// booleanReduceFloatIterator executes a reducer for every interval and buffers the result.
type booleanReduceFloatIterator struct {
	input    *bufBooleanIterator
	create   func() (BooleanPointAggregator, FloatPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []FloatPoint
	keepTags bool
}

func newBooleanReduceFloatIterator(input BooleanIterator, opt IteratorOptions, createFn func() (BooleanPointAggregator, FloatPointEmitter)) *booleanReduceFloatIterator {
	return &booleanReduceFloatIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanReduceFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanReduceFloatIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *booleanReduceFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// booleanReduceFloatPoint stores the reduced data for a name/tag combination.
type booleanReduceFloatPoint struct {
	Name       string
	Tags       Tags
	Aggregator BooleanPointAggregator
	Emitter    FloatPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *booleanReduceFloatIterator) reduce() ([]FloatPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*booleanReduceFloatPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]FloatPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(floatPointsByTime(a)))
	}
	return a, nil
}

// booleanStreamFloatIterator streams inputs into the iterator and emits points gradually.
type booleanStreamFloatIterator struct {
	input  *bufBooleanIterator
	create func() (BooleanPointAggregator, FloatPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*booleanReduceFloatPoint
	points []FloatPoint
}

// newBooleanStreamFloatIterator returns a new instance of booleanStreamFloatIterator.
func newBooleanStreamFloatIterator(input BooleanIterator, createFn func() (BooleanPointAggregator, FloatPointEmitter), opt IteratorOptions) *booleanStreamFloatIterator {
	return &booleanStreamFloatIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*booleanReduceFloatPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanStreamFloatIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanStreamFloatIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *booleanStreamFloatIterator) Next() (*FloatPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *booleanStreamFloatIterator) reduce() ([]FloatPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []FloatPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceFloatPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// booleanReduceIntegerIterator executes a reducer for every interval and buffers the result.
type booleanReduceIntegerIterator struct {
	input    *bufBooleanIterator
	create   func() (BooleanPointAggregator, IntegerPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []IntegerPoint
	keepTags bool
}

func newBooleanReduceIntegerIterator(input BooleanIterator, opt IteratorOptions, createFn func() (BooleanPointAggregator, IntegerPointEmitter)) *booleanReduceIntegerIterator {
	return &booleanReduceIntegerIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanReduceIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanReduceIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *booleanReduceIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// booleanReduceIntegerPoint stores the reduced data for a name/tag combination.
type booleanReduceIntegerPoint struct {
	Name       string
	Tags       Tags
	Aggregator BooleanPointAggregator
	Emitter    IntegerPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *booleanReduceIntegerIterator) reduce() ([]IntegerPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*booleanReduceIntegerPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]IntegerPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(integerPointsByTime(a)))
	}
	return a, nil
}

// booleanStreamIntegerIterator streams inputs into the iterator and emits points gradually.
type booleanStreamIntegerIterator struct {
	input  *bufBooleanIterator
	create func() (BooleanPointAggregator, IntegerPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*booleanReduceIntegerPoint
	points []IntegerPoint
}

// newBooleanStreamIntegerIterator returns a new instance of booleanStreamIntegerIterator.
func newBooleanStreamIntegerIterator(input BooleanIterator, createFn func() (BooleanPointAggregator, IntegerPointEmitter), opt IteratorOptions) *booleanStreamIntegerIterator {
	return &booleanStreamIntegerIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*booleanReduceIntegerPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanStreamIntegerIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanStreamIntegerIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *booleanStreamIntegerIterator) Next() (*IntegerPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *booleanStreamIntegerIterator) reduce() ([]IntegerPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []IntegerPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceIntegerPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// booleanReduceUnsignedIterator executes a reducer for every interval and buffers the result.
type booleanReduceUnsignedIterator struct {
	input    *bufBooleanIterator
	create   func() (BooleanPointAggregator, UnsignedPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []UnsignedPoint
	keepTags bool
}

func newBooleanReduceUnsignedIterator(input BooleanIterator, opt IteratorOptions, createFn func() (BooleanPointAggregator, UnsignedPointEmitter)) *booleanReduceUnsignedIterator {
	return &booleanReduceUnsignedIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanReduceUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanReduceUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *booleanReduceUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// booleanReduceUnsignedPoint stores the reduced data for a name/tag combination.
type booleanReduceUnsignedPoint struct {
	Name       string
	Tags       Tags
	Aggregator BooleanPointAggregator
	Emitter    UnsignedPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *booleanReduceUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*booleanReduceUnsignedPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]UnsignedPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(unsignedPointsByTime(a)))
	}
	return a, nil
}

// booleanStreamUnsignedIterator streams inputs into the iterator and emits points gradually.
type booleanStreamUnsignedIterator struct {
	input  *bufBooleanIterator
	create func() (BooleanPointAggregator, UnsignedPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*booleanReduceUnsignedPoint
	points []UnsignedPoint
}

// newBooleanStreamUnsignedIterator returns a new instance of booleanStreamUnsignedIterator.
func newBooleanStreamUnsignedIterator(input BooleanIterator, createFn func() (BooleanPointAggregator, UnsignedPointEmitter), opt IteratorOptions) *booleanStreamUnsignedIterator {
	return &booleanStreamUnsignedIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*booleanReduceUnsignedPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanStreamUnsignedIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanStreamUnsignedIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *booleanStreamUnsignedIterator) Next() (*UnsignedPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *booleanStreamUnsignedIterator) reduce() ([]UnsignedPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []UnsignedPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceUnsignedPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// booleanReduceStringIterator executes a reducer for every interval and buffers the result.
type booleanReduceStringIterator struct {
	input    *bufBooleanIterator
	create   func() (BooleanPointAggregator, StringPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []StringPoint
	keepTags bool
}

func newBooleanReduceStringIterator(input BooleanIterator, opt IteratorOptions, createFn func() (BooleanPointAggregator, StringPointEmitter)) *booleanReduceStringIterator {
	return &booleanReduceStringIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanReduceStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanReduceStringIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *booleanReduceStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// booleanReduceStringPoint stores the reduced data for a name/tag combination.
type booleanReduceStringPoint struct {
	Name       string
	Tags       Tags
	Aggregator BooleanPointAggregator
	Emitter    StringPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *booleanReduceStringIterator) reduce() ([]StringPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*booleanReduceStringPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]StringPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(stringPointsByTime(a)))
	}
	return a, nil
}

// booleanStreamStringIterator streams inputs into the iterator and emits points gradually.
type booleanStreamStringIterator struct {
	input  *bufBooleanIterator
	create func() (BooleanPointAggregator, StringPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*booleanReduceStringPoint
	points []StringPoint
}

// newBooleanStreamStringIterator returns a new instance of booleanStreamStringIterator.
func newBooleanStreamStringIterator(input BooleanIterator, createFn func() (BooleanPointAggregator, StringPointEmitter), opt IteratorOptions) *booleanStreamStringIterator {
	return &booleanStreamStringIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*booleanReduceStringPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanStreamStringIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanStreamStringIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *booleanStreamStringIterator) Next() (*StringPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *booleanStreamStringIterator) reduce() ([]StringPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []StringPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceStringPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// booleanReduceBooleanIterator executes a reducer for every interval and buffers the result.
type booleanReduceBooleanIterator struct {
	input    *bufBooleanIterator
	create   func() (BooleanPointAggregator, BooleanPointEmitter)
	dims     []string
	opt      IteratorOptions
	points   []BooleanPoint
	keepTags bool
}

func newBooleanReduceBooleanIterator(input BooleanIterator, opt IteratorOptions, createFn func() (BooleanPointAggregator, BooleanPointEmitter)) *booleanReduceBooleanIterator {
	return &booleanReduceBooleanIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanReduceBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanReduceBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the minimum value for the next available interval.
func (itr *booleanReduceBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// booleanReduceBooleanPoint stores the reduced data for a name/tag combination.
type booleanReduceBooleanPoint struct {
	Name       string
	Tags       Tags
	Aggregator BooleanPointAggregator
	Emitter    BooleanPointEmitter
}

// reduce executes fn once for every point in the next window.
// The previous value for the dimension is passed to fn.
func (itr *booleanReduceBooleanIterator) reduce() ([]BooleanPoint, error) {
	// Calculate next window.
	var (
		startTime, endTime int64
		window             struct {
			name string
			tags string
		}
	)
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		} else if p.Nil {
			continue
		}

		// Unread the point so it can be processed.
		itr.input.unread(p)
		startTime, endTime = itr.opt.Window(p.Time)
		window.name, window.tags = p.Name, p.Tags.Subset(itr.opt.Dimensions).ID()
		break
	}

	// Create points by tags.
	m := make(map[string]*booleanReduceBooleanPoint)
	for {
		// Read next point.
		curr, err := itr.input.NextInWindow(startTime, endTime)
		if err != nil {
			return nil, err
		} else if curr == nil {
			break
		} else if curr.Nil {
			continue
		} else if curr.Name != window.name {
			itr.input.unread(curr)
			break
		}

		// Ensure this point is within the same final window.
		if curr.Name != window.name {
			itr.input.unread(curr)
			break
		} else if tags := curr.Tags.Subset(itr.opt.Dimensions); tags.ID() != window.tags {
			itr.input.unread(curr)
			break
		}

		// Retrieve the tags on this point for this level of the query.
		// This may be different than the bucket dimensions.
		tags := curr.Tags.Subset(itr.dims)
		id := tags.ID()

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)
	}

	// Reverse sort points by name & tag if our output is supposed to be ordered.
	// This is because the final array needs to have the first
	// point at the end since they are popped off of the end.
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	if len(keys) > 1 && itr.opt.Ordered {
		sort.Sort(reverseStringSlice(keys))
	}

	// Assume the points are already sorted until proven otherwise.
	sortedByTime := true
	// Emit the points for each name & tag combination.
	a := make([]BooleanPoint, 0, len(m))
	for _, k := range keys {
		rp := m[k]
		points := rp.Emitter.Emit()
		for i := len(points) - 1; i >= 0; i-- {
			points[i].Name = rp.Name
			if !itr.keepTags {
				points[i].Tags = rp.Tags
			}
			// Set the points time to the interval time if the reducer didn't provide one.
			if points[i].Time == ZeroTime {
				points[i].Time = startTime
			} else {
				sortedByTime = false
			}
			a = append(a, points[i])
		}
	}
	// Points may be out of order. Perform a stable sort by time if requested.
	if !sortedByTime && itr.opt.Ordered {
		sort.Stable(sort.Reverse(booleanPointsByTime(a)))
	}
	return a, nil
}

// booleanStreamBooleanIterator streams inputs into the iterator and emits points gradually.
type booleanStreamBooleanIterator struct {
	input  *bufBooleanIterator
	create func() (BooleanPointAggregator, BooleanPointEmitter)
	dims   []string
	opt    IteratorOptions
	m      map[string]*booleanReduceBooleanPoint
	points []BooleanPoint
}

// newBooleanStreamBooleanIterator returns a new instance of booleanStreamBooleanIterator.
func newBooleanStreamBooleanIterator(input BooleanIterator, createFn func() (BooleanPointAggregator, BooleanPointEmitter), opt IteratorOptions) *booleanStreamBooleanIterator {
	return &booleanStreamBooleanIterator{
		input:  newBufBooleanIterator(input),
		create: createFn,
		dims:   opt.GetDimensions(),
		opt:    opt,
		m:      make(map[string]*booleanReduceBooleanPoint),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanStreamBooleanIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanStreamBooleanIterator) Close() error { return itr.input.Close() }

// Next returns the next value for the stream iterator.
func (itr *booleanStreamBooleanIterator) Next() (*BooleanPoint, error) {
	// Calculate next window if we have no more points.
	if len(itr.points) == 0 {
		var err error
		itr.points, err = itr.reduce()
		if len(itr.points) == 0 {
			return nil, err
		}
	}

	// Pop next point off the stack.
	p := &itr.points[len(itr.points)-1]
	itr.points = itr.points[:len(itr.points)-1]
	return p, nil
}

// reduce creates and manages aggregators for every point from the input.
// After aggregating a point, it always tries to emit a value using the emitter.
func (itr *booleanStreamBooleanIterator) reduce() ([]BooleanPoint, error) {
	// We have already read all of the input points.
	if itr.m == nil {
		return nil, nil
	}

	for {
		// Read next point.
		curr, err := itr.input.Next()
		if err != nil {
			return nil, err
		} else if curr == nil {
			// Close all of the aggregators to flush any remaining points to emit.
			var points []BooleanPoint
			for _, rp := range itr.m {
				if aggregator, ok := rp.Aggregator.(io.Closer); ok {
					if err := aggregator.Close(); err != nil {
						return nil, err
					}

					pts := rp.Emitter.Emit()
					if len(pts) == 0 {
						continue
					}

					for i := range pts {
						pts[i].Name = rp.Name
						pts[i].Tags = rp.Tags
					}
					points = append(points, pts...)
				}
			}

			// Eliminate the aggregators and emitters.
			itr.m = nil
			return points, nil
		} else if curr.Nil {
			continue
		}
		tags := curr.Tags.Subset(itr.dims)

		id := curr.Name
		if len(tags.m) > 0 {
			id += "\x00" + tags.ID()
		}

		// Retrieve the aggregator for this name/tag combination or create one.
		rp := itr.m[id]
		if rp == nil {
			aggregator, emitter := itr.create()
			rp = &booleanReduceBooleanPoint{
				Name:       curr.Name,
				Tags:       tags,
				Aggregator: aggregator,
				Emitter:    emitter,
			}
			itr.m[id] = rp
		}
		rp.Aggregator.AggregateBoolean(curr)

		// Attempt to emit points from the aggregator.
		points := rp.Emitter.Emit()
		if len(points) == 0 {
			continue
		}

		for i := range points {
			points[i].Name = rp.Name
			points[i].Tags = rp.Tags
		}
		return points, nil
	}
}

// booleanDedupeIterator only outputs unique points.
// This differs from the DistinctIterator in that it compares all aux fields too.
// This iterator is relatively inefficient and should only be used on small
// datasets such as meta query results.
type booleanDedupeIterator struct {
	input BooleanIterator
	m     map[string]struct{} // lookup of points already sent
}

type booleanIteratorMapper struct {
	cur    Cursor
	row    Row
	driver IteratorMap   // which iterator to use for the primary value, can be nil
	fields []IteratorMap // which iterator to use for an aux field
	point  BooleanPoint
}

func newBooleanIteratorMapper(cur Cursor, driver IteratorMap, fields []IteratorMap, opt IteratorOptions) *booleanIteratorMapper {
	return &booleanIteratorMapper{
		cur:    cur,
		driver: driver,
		fields: fields,
		point: BooleanPoint{
			Aux: make([]interface{}, len(fields)),
		},
	}
}

func (itr *booleanIteratorMapper) Next() (*BooleanPoint, error) {
	if !itr.cur.Scan(&itr.row) {
		if err := itr.cur.Err(); err != nil {
			return nil, err
		}
		return nil, nil
	}

	itr.point.Time = itr.row.Time
	itr.point.Name = itr.row.Series.Name
	itr.point.Tags = itr.row.Series.Tags

	if itr.driver != nil {
		if v := itr.driver.Value(&itr.row); v != nil {
			if v, ok := castToBoolean(v); ok {
				itr.point.Value = v
				itr.point.Nil = false
			} else {
				itr.point.Value = false
				itr.point.Nil = true
			}
		} else {
			itr.point.Value = false
			itr.point.Nil = true
		}
	}
	for i, f := range itr.fields {
		itr.point.Aux[i] = f.Value(&itr.row)
	}
	return &itr.point, nil
}

func (itr *booleanIteratorMapper) Stats() IteratorStats {
	return itr.cur.Stats()
}

func (itr *booleanIteratorMapper) Close() error {
	return itr.cur.Close()
}

type booleanFilterIterator struct {
	input BooleanIterator
	cond  influxql.Expr
	opt   IteratorOptions
	m     map[string]interface{}
}

func newBooleanFilterIterator(input BooleanIterator, cond influxql.Expr, opt IteratorOptions) BooleanIterator {
	// Strip out time conditions from the WHERE clause.
	// TODO(jsternberg): This should really be done for us when creating the IteratorOptions struct.
	n := influxql.RewriteFunc(influxql.CloneExpr(cond), func(n influxql.Node) influxql.Node {
		switch n := n.(type) {
		case *influxql.BinaryExpr:
			if n.LHS.String() == "time" {
				return &influxql.BooleanLiteral{Val: true}
			}
		}
		return n
	})

	cond, _ = n.(influxql.Expr)
	if cond == nil {
		return input
	} else if n, ok := cond.(*influxql.BooleanLiteral); ok && n.Val {
		return input
	}

	return &booleanFilterIterator{
		input: input,
		cond:  cond,
		opt:   opt,
		m:     make(map[string]interface{}),
	}
}

func (itr *booleanFilterIterator) Stats() IteratorStats { return itr.input.Stats() }
func (itr *booleanFilterIterator) Close() error         { return itr.input.Close() }

func (itr *booleanFilterIterator) Next() (*BooleanPoint, error) {
	for {
		p, err := itr.input.Next()
		if err != nil || p == nil {
			return nil, err
		}

		for i, ref := range itr.opt.Aux {
			itr.m[ref.Val] = p.Aux[i]
		}
		for k, v := range p.Tags.KeyValues() {
			itr.m[k] = v
		}

		if !influxql.EvalBool(itr.cond, itr.m) {
			continue
		}
		return p, nil
	}
}

type booleanTagSubsetIterator struct {
	input      BooleanIterator
	point      BooleanPoint
	lastTags   Tags
	dimensions []string
}

func newBooleanTagSubsetIterator(input BooleanIterator, opt IteratorOptions) *booleanTagSubsetIterator {
	return &booleanTagSubsetIterator{
		input:      input,
		dimensions: opt.GetDimensions(),
	}
}

func (itr *booleanTagSubsetIterator) Next() (*BooleanPoint, error) {
	p, err := itr.input.Next()
	if err != nil {
		return nil, err
	} else if p == nil {
		return nil, nil
	}

	itr.point.Name = p.Name
	if !p.Tags.Equal(itr.lastTags) {
		itr.point.Tags = p.Tags.Subset(itr.dimensions)
		itr.lastTags = p.Tags
	}
	itr.point.Time = p.Time
	itr.point.Value = p.Value
	itr.point.Aux = p.Aux
	itr.point.Aggregated = p.Aggregated
	itr.point.Nil = p.Nil
	return &itr.point, nil
}

func (itr *booleanTagSubsetIterator) Stats() IteratorStats {
	return itr.input.Stats()
}

func (itr *booleanTagSubsetIterator) Close() error {
	return itr.input.Close()
}

// newBooleanDedupeIterator returns a new instance of booleanDedupeIterator.
func newBooleanDedupeIterator(input BooleanIterator) *booleanDedupeIterator {
	return &booleanDedupeIterator{
		input: input,
		m:     make(map[string]struct{}),
	}
}

// Stats returns stats from the input iterator.
func (itr *booleanDedupeIterator) Stats() IteratorStats { return itr.input.Stats() }

// Close closes the iterator and all child iterators.
func (itr *booleanDedupeIterator) Close() error { return itr.input.Close() }

// Next returns the next unique point from the input iterator.
func (itr *booleanDedupeIterator) Next() (*BooleanPoint, error) {
	for {
		// Read next point.
		p, err := itr.input.Next()
		if p == nil || err != nil {
			return nil, err
		}

		// Serialize to bytes to store in lookup.
		buf, err := proto.Marshal(encodeBooleanPoint(p))
		if err != nil {
			return nil, err
		}

		// If the point has already been output then move to the next point.
		if _, ok := itr.m[string(buf)]; ok {
			continue
		}

		// Otherwise mark it as emitted and return point.
		itr.m[string(buf)] = struct{}{}
		return p, nil
	}
}

// booleanReaderIterator represents an iterator that streams from a reader.
type booleanReaderIterator struct {
	r   io.Reader
	dec *BooleanPointDecoder
}

// newBooleanReaderIterator returns a new instance of booleanReaderIterator.
func newBooleanReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *booleanReaderIterator {
	dec := NewBooleanPointDecoder(ctx, r)
	dec.stats = stats

	return &booleanReaderIterator{
		r:   r,
		dec: dec,
	}
}

// Stats returns stats about points processed.
func (itr *booleanReaderIterator) Stats() IteratorStats { return itr.dec.stats }

// Close closes the underlying reader, if applicable.
func (itr *booleanReaderIterator) Close() error {
	if r, ok := itr.r.(io.ReadCloser); ok {
		return r.Close()
	}
	return nil
}

// Next returns the next point from the iterator.
func (itr *booleanReaderIterator) Next() (*BooleanPoint, error) {
	// OPTIMIZE(benbjohnson): Reuse point on iterator.

	// Unmarshal next point.
	p := &BooleanPoint{}
	if err := itr.dec.DecodeBooleanPoint(p); err == io.EOF {
		return nil, nil
	} else if err != nil {
		return nil, err
	}
	return p, nil
}

// encodeFloatIterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encodeFloatIterator(itr FloatIterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := NewFloatPointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.EncodeFloatPoint(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}

// encodeIntegerIterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encodeIntegerIterator(itr IntegerIterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := NewIntegerPointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.EncodeIntegerPoint(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}

// encodeUnsignedIterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encodeUnsignedIterator(itr UnsignedIterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := NewUnsignedPointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.EncodeUnsignedPoint(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}

// encodeStringIterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encodeStringIterator(itr StringIterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := NewStringPointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.EncodeStringPoint(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}

// encodeBooleanIterator encodes all points from itr to the underlying writer.
func (enc *IteratorEncoder) encodeBooleanIterator(itr BooleanIterator) error {
	ticker := time.NewTicker(enc.StatsInterval)
	defer ticker.Stop()

	// Emit initial stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}

	// Continually stream points from the iterator into the encoder.
	penc := NewBooleanPointEncoder(enc.w)
	for {
		// Emit stats periodically.
		select {
		case <-ticker.C:
			if err := enc.encodeStats(itr.Stats()); err != nil {
				return err
			}
		default:
		}

		// Retrieve the next point from the iterator.
		p, err := itr.Next()
		if err != nil {
			return err
		} else if p == nil {
			break
		}

		// Write the point to the point encoder.
		if err := penc.EncodeBooleanPoint(p); err != nil {
			return err
		}
	}

	// Emit final stats.
	if err := enc.encodeStats(itr.Stats()); err != nil {
		return err
	}
	return nil
}