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compact.go
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compact.go
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package tsm1
// Compactions are the process of creating read-optimized TSM files.
// The files are created by converting write-optimized WAL entries
// to read-optimized TSM format. They can also be created from existing
// TSM files when there are tombstone records that neeed to be removed, points
// that were overwritten by later writes and need to updated, or multiple
// smaller TSM files need to be merged to reduce file counts and improve
// compression ratios.
//
// The the compaction process is stream-oriented using multiple readers and
// iterators. The resulting stream is written sorted and chunked to allow for
// one-pass writing of a new TSM file.
import (
"fmt"
"math"
"os"
"path/filepath"
"sort"
"sync"
"time"
"github.com/influxdata/influxdb/tsdb"
)
const maxTSMFileSize = uint32(2048 * 1024 * 1024) // 2GB
const (
CompactionTempExtension = "tmp"
TSMFileExtension = "tsm"
)
var (
errMaxFileExceeded = fmt.Errorf("max file exceeded")
errSnapshotsDisabled = fmt.Errorf("snapshots disabled")
errCompactionsDisabled = fmt.Errorf("compactions disabled")
errCompactionAborted = fmt.Errorf("compaction aborted")
errCompactionInProgress = fmt.Errorf("compaction in progress")
)
var (
MaxTime = time.Unix(0, math.MaxInt64)
MinTime = time.Unix(0, 0)
)
type CompactionGroup []string
// CompactionPlanner determines what TSM files and WAL segments to include in a
// given compaction run.
type CompactionPlanner interface {
Plan(lastWrite time.Time) []CompactionGroup
PlanLevel(level int) []CompactionGroup
PlanOptimize() []CompactionGroup
}
// DefaultPlanner implements CompactionPlanner using a strategy to roll up
// multiple generations of TSM files into larger files in stages. It attempts
// to minimize the number of TSM files on disk while rolling up a bounder number
// of files.
type DefaultPlanner struct {
FileStore interface {
Stats() []FileStat
LastModified() time.Time
BlockCount(path string, idx int) int
}
// CompactFullWriteColdDuration specifies the length of time after
// which if no writes have been committed to the WAL, the engine will
// do a full compaction of the TSM files in this shard. This duration
// should always be greater than the CacheFlushWriteColdDuraion
CompactFullWriteColdDuration time.Duration
// lastPlanCheck is the last time Plan was called
lastPlanCheck time.Time
}
// tsmGeneration represents the TSM files within a generation.
// 000001-01.tsm, 000001-02.tsm would be in the same generation
// 000001 each with different sequence numbers.
type tsmGeneration struct {
id int
files []FileStat
}
// size returns the total size of the generation
func (t *tsmGeneration) size() uint64 {
var n uint64
for _, f := range t.files {
n += uint64(f.Size)
}
return n
}
// compactionLevel returns the level of the files in this generation
func (t *tsmGeneration) level() int {
// Level 0 is always created from the result of a cache compaction. It generates
// 1 file with a sequence num of 1. Level 2 is generated by compacting multiple
// level 1 files. Level 3 is generate by compacting multiple level 2 files. Level
// 4 is for anything else.
_, seq, _ := ParseTSMFileName(t.files[0].Path)
if seq < 4 {
return seq
}
return 4
}
func (t *tsmGeneration) lastModified() int64 {
var max int64
for _, f := range t.files {
if f.LastModified > max {
max = f.LastModified
}
}
return max
}
// count return then number of files in the generation
func (t *tsmGeneration) count() int {
return len(t.files)
}
// hasTombstones returns true if there a keys removed for any of the files
func (t *tsmGeneration) hasTombstones() bool {
for _, f := range t.files {
if f.HasTombstone {
return true
}
}
return false
}
// PlanLevel returns a set of TSM files to rewrite for a specific level
func (c *DefaultPlanner) PlanLevel(level int) []CompactionGroup {
// Determine the generations from all files on disk. We need to treat
// a generation conceptually as a single file even though it may be
// split across several files in sequence.
generations := c.findGenerations()
// If there is only one generation and no tombstones, then there's nothing to
// do.
if len(generations) <= 1 && !generations.hasTombstones() {
return nil
}
// Group each generation by level such that two adjacent generations in the same
// level become part of the same group.
var currentGen tsmGenerations
var groups []tsmGenerations
for i := 0; i < len(generations); i++ {
cur := generations[i]
if len(currentGen) == 0 || currentGen[0].level() == cur.level() {
currentGen = append(currentGen, cur)
continue
}
groups = append(groups, currentGen)
currentGen = tsmGenerations{}
currentGen = append(currentGen, cur)
}
if len(currentGen) > 0 {
groups = append(groups, currentGen)
}
// Remove any groups in the wrong level
var levelGroups []tsmGenerations
for _, cur := range groups {
if cur[0].level() == level {
levelGroups = append(levelGroups, cur)
}
}
// Determine the minimum number of files required for the level. Higher levels are more
// CPU intensive so we only want to include them when we have enough data to make them
// worthwhile.
// minGenerations 1 -> 2
// minGenerations 2 -> 2
// minGenerations 3 -> 4
// minGenerations 4 -> 4
minGenerations := level
if minGenerations%2 != 0 {
minGenerations = level + 1
}
var cGroups []CompactionGroup
for _, group := range levelGroups {
for _, chunk := range group.chunk(4) {
var cGroup CompactionGroup
var hasTombstones bool
for _, gen := range chunk {
if gen.hasTombstones() {
hasTombstones = true
}
for _, file := range gen.files {
cGroup = append(cGroup, file.Path)
}
}
if len(chunk) < minGenerations && !hasTombstones {
continue
}
cGroups = append(cGroups, cGroup)
}
}
return cGroups
}
// PlanOptimize returns all TSM files if they are in different generations in order
// to optimize the index across TSM files. Each returned compaction group can be
// compacted concurrently.
func (c *DefaultPlanner) PlanOptimize() []CompactionGroup {
// Determine the generations from all files on disk. We need to treat
// a generation conceptually as a single file even though it may be
// split across several files in sequence.
generations := c.findGenerations()
// If there is only one generation and no tombstones, then there's nothing to
// do.
if len(generations) <= 1 && !generations.hasTombstones() {
return nil
}
// Group each generation by level such that two adjacent generations in the same
// level become part of the same group.
var currentGen tsmGenerations
var groups []tsmGenerations
for i := 0; i < len(generations); i++ {
cur := generations[i]
if len(currentGen) == 0 || currentGen[0].level() == cur.level() {
currentGen = append(currentGen, cur)
continue
}
groups = append(groups, currentGen)
currentGen = tsmGenerations{}
currentGen = append(currentGen, cur)
}
if len(currentGen) > 0 {
groups = append(groups, currentGen)
}
// Only optimize level 4 files since using lower-levels will collide
// with the level planners
var levelGroups []tsmGenerations
for _, cur := range groups {
if cur[0].level() == 4 {
levelGroups = append(levelGroups, cur)
}
}
var cGroups []CompactionGroup
for _, group := range levelGroups {
// Skip the group if it's not worthwhile to optimize it
if len(group) < 4 && !group.hasTombstones() {
continue
}
var cGroup CompactionGroup
for _, gen := range group {
for _, file := range gen.files {
cGroup = append(cGroup, file.Path)
}
}
cGroups = append(cGroups, cGroup)
}
return cGroups
}
// Plan returns a set of TSM files to rewrite for level 4 or higher. The planning returns
// multiple groups if possible to allow compactions to run concurrently.
func (c *DefaultPlanner) Plan(lastWrite time.Time) []CompactionGroup {
generations := c.findGenerations()
// first check if we should be doing a full compaction because nothing has been written in a long time
if c.CompactFullWriteColdDuration > 0 && time.Now().Sub(lastWrite) > c.CompactFullWriteColdDuration && len(generations) > 1 {
var tsmFiles []string
var genCount int
for i, group := range generations {
var skip bool
// Skip the file if it's over the max size and contains a full block and it does not have any tombstones
if len(generations) > 2 && group.size() > uint64(maxTSMFileSize) && c.FileStore.BlockCount(group.files[0].Path, 1) == tsdb.DefaultMaxPointsPerBlock && !group.hasTombstones() {
skip = true
}
// We need to look at the level of the next file because it may need to be combined with this generation
// but won't get picked up on it's own if this generation is skipped. This allows the most recently
// created files to get picked up by the full compaction planner and avoids having a few less optimally
// compressed files.
if i < len(generations)-1 {
if generations[i+1].level() <= 3 {
skip = false
}
}
if skip {
continue
}
for _, f := range group.files {
tsmFiles = append(tsmFiles, f.Path)
}
genCount += 1
}
sort.Strings(tsmFiles)
// Make sure we have more than 1 file and more than 1 generation
if len(tsmFiles) <= 1 || genCount <= 1 {
return nil
}
return []CompactionGroup{tsmFiles}
}
// don't plan if nothing has changed in the filestore
if c.lastPlanCheck.After(c.FileStore.LastModified()) && !generations.hasTombstones() {
return nil
}
c.lastPlanCheck = time.Now()
// If there is only one generation, return early to avoid re-compacting the same file
// over and over again.
if len(generations) <= 1 && !generations.hasTombstones() {
return nil
}
// Need to find the ending point for level 4 files. They will be the oldest files. We scan
// each generation in descending break once we see a file less than 4.
end := 0
start := 0
for i, g := range generations {
if g.level() <= 3 {
break
}
end = i + 1
}
// As compactions run, the oldest files get bigger. We don't want to re-compact them during
// this planning if they are maxed out so skip over any we see.
var hasTombstones bool
for i, g := range generations[:end] {
if g.hasTombstones() {
hasTombstones = true
}
if hasTombstones {
continue
}
// Skip the file if it's over the max size and contains a full block or the generation is split
// over multiple files. In the latter case, that would mean the data in the file spilled over
// the 2GB limit.
if g.size() > uint64(maxTSMFileSize) && c.FileStore.BlockCount(g.files[0].Path, 1) == tsdb.DefaultMaxPointsPerBlock || g.count() > 1 {
start = i + 1
}
// This is an edge case that can happen after multiple compactions run. The files at the beginning
// can become larger faster than ones after them. We want to skip those really big ones and just
// compact the smaller ones until they are closer in size.
if i > 0 {
if g.size()*2 < generations[i-1].size() {
start = i
break
}
}
}
// step is how may files to compact in a group. We want to clamp it at 4 but also stil
// return groups smaller than 4.
step := 4
if step > end {
step = end
}
// slice off the generations that we'll examine
generations = generations[start:end]
// Loop through the generations in groups of size step and see if we can compact all (or
// some of them as group)
groups := []tsmGenerations{}
for i := 0; i < len(generations); i += step {
var skipGroup bool
startIndex := i
for j := i; j < i+step && j < len(generations); j++ {
gen := generations[j]
lvl := gen.level()
// Skip compacting this group if there happens to be any lower level files in the
// middle. These will get picked up by the level compactors.
if lvl <= 3 {
skipGroup = true
break
}
// Skip the file if it's over the max size and it contains a full block
if gen.size() >= uint64(maxTSMFileSize) && c.FileStore.BlockCount(gen.files[0].Path, 1) == tsdb.DefaultMaxPointsPerBlock && !gen.hasTombstones() {
startIndex++
continue
}
}
if skipGroup {
continue
}
endIndex := i + step
if endIndex > len(generations) {
endIndex = len(generations)
}
if endIndex-startIndex > 0 {
groups = append(groups, generations[startIndex:endIndex])
}
}
if len(groups) == 0 {
return nil
}
// With the groups, we need to evaluate whether the group as a whole can be compacted
compactable := []tsmGenerations{}
for _, group := range groups {
//if we don't have enough generations to compact, skip it
if len(group) < 2 && !group.hasTombstones() {
continue
}
compactable = append(compactable, group)
}
// All the files to be compacted must be compacted in order. We need to convert each
// group to the actual set of files in that group to be compacted.
var tsmFiles []CompactionGroup
for _, c := range compactable {
var cGroup CompactionGroup
for _, group := range c {
for _, f := range group.files {
cGroup = append(cGroup, f.Path)
}
}
sort.Strings(cGroup)
tsmFiles = append(tsmFiles, cGroup)
}
return tsmFiles
}
// findGenerations groups all the TSM files by they generation based
// on their filename then returns the generations in descending order (newest first)
func (c *DefaultPlanner) findGenerations() tsmGenerations {
tsmStats := c.FileStore.Stats()
generations := make(map[int]*tsmGeneration, len(tsmStats))
for _, f := range tsmStats {
gen, _, _ := ParseTSMFileName(f.Path)
group := generations[gen]
if group == nil {
group = &tsmGeneration{
id: gen,
}
generations[gen] = group
}
group.files = append(group.files, f)
}
orderedGenerations := make(tsmGenerations, 0, len(generations))
for _, g := range generations {
orderedGenerations = append(orderedGenerations, g)
}
sort.Sort(orderedGenerations)
return orderedGenerations
}
// Compactor merges multiple TSM files into new files or
// writes a Cache into 1 or more TSM files
type Compactor struct {
Dir string
Size int
FileStore interface {
NextGeneration() int
}
mu sync.RWMutex
snapshotsEnabled bool
compactionsEnabled bool
files map[string]struct{}
}
func (c *Compactor) Open() {
c.mu.Lock()
defer c.mu.Unlock()
if c.snapshotsEnabled || c.compactionsEnabled {
return
}
c.snapshotsEnabled = true
c.compactionsEnabled = true
c.files = make(map[string]struct{})
}
func (c *Compactor) Close() {
c.mu.Lock()
defer c.mu.Unlock()
if !(c.snapshotsEnabled || c.compactionsEnabled) {
return
}
c.snapshotsEnabled = false
c.compactionsEnabled = false
}
func (c *Compactor) DisableSnapshots() {
c.mu.Lock()
c.snapshotsEnabled = false
c.mu.Unlock()
}
func (c *Compactor) EnableSnapshots() {
c.mu.Lock()
c.snapshotsEnabled = true
c.mu.Unlock()
}
func (c *Compactor) DisableCompactions() {
c.mu.Lock()
c.compactionsEnabled = false
c.mu.Unlock()
}
func (c *Compactor) EnableCompactions() {
c.mu.Lock()
c.compactionsEnabled = true
c.mu.Unlock()
}
// WriteSnapshot will write a Cache snapshot to a new TSM files.
func (c *Compactor) WriteSnapshot(cache *Cache) ([]string, error) {
c.mu.RLock()
enabled := c.snapshotsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errSnapshotsDisabled
}
iter := NewCacheKeyIterator(cache, tsdb.DefaultMaxPointsPerBlock)
files, err := c.writeNewFiles(c.FileStore.NextGeneration(), 0, iter)
// See if we were disabled while writing a snapshot
c.mu.RLock()
enabled = c.snapshotsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errSnapshotsDisabled
}
return files, err
}
// Compact will write multiple smaller TSM files into 1 or more larger files
func (c *Compactor) compact(fast bool, tsmFiles []string) ([]string, error) {
size := c.Size
if size <= 0 {
size = tsdb.DefaultMaxPointsPerBlock
}
// The new compacted files need to added to the max generation in the
// set. We need to find that max generation as well as the max sequence
// number to ensure we write to the next unique location.
var maxGeneration, maxSequence int
for _, f := range tsmFiles {
gen, seq, err := ParseTSMFileName(f)
if err != nil {
return nil, err
}
if gen > maxGeneration {
maxGeneration = gen
maxSequence = seq
}
if gen == maxGeneration && seq > maxSequence {
maxSequence = seq
}
}
// For each TSM file, create a TSM reader
var trs []*TSMReader
for _, file := range tsmFiles {
f, err := os.Open(file)
if err != nil {
return nil, err
}
tr, err := NewTSMReader(f)
if err != nil {
return nil, err
}
defer tr.Close()
trs = append(trs, tr)
}
if len(trs) == 0 {
return nil, nil
}
tsm, err := NewTSMKeyIterator(size, fast, trs...)
if err != nil {
return nil, err
}
return c.writeNewFiles(maxGeneration, maxSequence, tsm)
}
// Compact will write multiple smaller TSM files into 1 or more larger files
func (c *Compactor) CompactFull(tsmFiles []string) ([]string, error) {
c.mu.RLock()
enabled := c.compactionsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errCompactionsDisabled
}
if !c.add(tsmFiles) {
return nil, errCompactionInProgress
}
defer c.remove(tsmFiles)
files, err := c.compact(false, tsmFiles)
// See if we were disabled while writing a snapshot
c.mu.RLock()
enabled = c.compactionsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errCompactionsDisabled
}
return files, err
}
// Compact will write multiple smaller TSM files into 1 or more larger files
func (c *Compactor) CompactFast(tsmFiles []string) ([]string, error) {
c.mu.RLock()
enabled := c.compactionsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errCompactionsDisabled
}
if !c.add(tsmFiles) {
return nil, errCompactionInProgress
}
defer c.remove(tsmFiles)
files, err := c.compact(true, tsmFiles)
// See if we were disabled while writing a snapshot
c.mu.RLock()
enabled = c.compactionsEnabled
c.mu.RUnlock()
if !enabled {
return nil, errCompactionsDisabled
}
return files, err
}
// writeNewFiles will write from the iterator into new TSM files, rotating
// to a new file when we've reached the max TSM file size
func (c *Compactor) writeNewFiles(generation, sequence int, iter KeyIterator) ([]string, error) {
// These are the new TSM files written
var files []string
for {
sequence++
// New TSM files are written to a temp file and renamed when fully completed.
fileName := filepath.Join(c.Dir, fmt.Sprintf("%09d-%09d.%s.tmp", generation, sequence, TSMFileExtension))
// Write as much as possible to this file
err := c.write(fileName, iter)
// We've hit the max file limit and there is more to write. Create a new file
// and continue.
if err == errMaxFileExceeded || err == ErrMaxBlocksExceeded {
files = append(files, fileName)
continue
} else if err == ErrNoValues {
// If the file only contained tombstoned entries, then it would be a 0 length
// file that we can drop.
if err := os.RemoveAll(fileName); err != nil {
return nil, err
}
break
}
// We hit an error but didn't finish the compaction. Remove the temp file and abort.
if err != nil {
return nil, err
}
files = append(files, fileName)
break
}
return files, nil
}
func (c *Compactor) write(path string, iter KeyIterator) (err error) {
fd, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_EXCL, 0666)
if err != nil {
return errCompactionInProgress
}
// Create the write for the new TSM file.
w, err := NewTSMWriter(fd)
if err != nil {
return err
}
defer func() {
closeErr := w.Close()
if err == nil {
err = closeErr
}
}()
for iter.Next() {
c.mu.RLock()
enabled := c.snapshotsEnabled || c.compactionsEnabled
c.mu.RUnlock()
if !enabled {
return errCompactionAborted
}
// Each call to read returns the next sorted key (or the prior one if there are
// more values to write). The size of values will be less than or equal to our
// chunk size (1000)
key, minTime, maxTime, block, err := iter.Read()
if err != nil {
return err
}
// Write the key and value
if err := w.WriteBlock(key, minTime, maxTime, block); err == ErrMaxBlocksExceeded {
if err := w.WriteIndex(); err != nil {
return err
}
return err
} else if err != nil {
return err
}
// If we have a max file size configured and we're over it, close out the file
// and return the error.
if w.Size() > maxTSMFileSize {
if err := w.WriteIndex(); err != nil {
return err
}
return errMaxFileExceeded
}
}
// We're all done. Close out the file.
if err := w.WriteIndex(); err != nil {
return err
}
return nil
}
func (c *Compactor) add(files []string) bool {
c.mu.Lock()
defer c.mu.Unlock()
// See if the new files are already in use
for _, f := range files {
if _, ok := c.files[f]; ok {
return false
}
}
// Mark all the new files in use
for _, f := range files {
c.files[f] = struct{}{}
}
return true
}
func (c *Compactor) remove(files []string) {
c.mu.Lock()
defer c.mu.Unlock()
for _, f := range files {
delete(c.files, f)
}
}
// KeyIterator allows iteration over set of keys and values in sorted order.
type KeyIterator interface {
Next() bool
Read() (string, int64, int64, []byte, error)
Close() error
}
// tsmKeyIterator implements the KeyIterator for set of TSMReaders. Iteration produces
// keys in sorted order and the values between the keys sorted and deduped. If any of
// the readers have associated tombstone entries, they are returned as part of iteration.
type tsmKeyIterator struct {
// readers is the set of readers it produce a sorted key run with
readers []*TSMReader
// values is the temporary buffers for each key that is returned by a reader
values map[string][]Value
// pos is the current key postion within the corresponding readers slice. A value of
// pos[0] = 1, means the reader[0] is currently at key 1 in its ordered index.
pos []int
keys []string
// err is any error we received while iterating values.
err error
// indicates whether the iterator should choose a faster merging strategy over a more
// optimally compressed one. If fast is true, multiple blocks will just be added as is
// and not combined. In some cases, a slower path will need to be utilized even when
// fast is true to prevent overlapping blocks of time for the same key.
// If false, the blocks will be decoded and duplicated (if needed) and
// then chunked into the maximally sized blocks.
fast bool
// size is the maximum number of values to encode in a single block
size int
// key is the current key lowest key across all readers that has not be fully exhausted
// of values.
key string
iterators []*BlockIterator
blocks blocks
buf []blocks
// mergeValues are decoded blocks that have been combined
mergedValues Values
// merged are encoded blocks that have been combined or used as is
// without decode
merged blocks
}
type block struct {
key string
minTime, maxTime int64
b []byte
tombstones []TimeRange
// readMin, readMax are the timestamps range of values have been
// read and encoded from this block.
readMin, readMax int64
}
func (b *block) overlapsTimeRange(min, max int64) bool {
return b.minTime <= max && b.maxTime >= min
}
func (b *block) read() bool {
return b.readMin <= b.minTime && b.readMax >= b.maxTime
}
func (b *block) markRead(min, max int64) {
if min < b.readMin {
b.readMin = min
}
if max > b.readMax {
b.readMax = max
}
}
type blocks []*block
func (a blocks) Len() int { return len(a) }
func (a blocks) Less(i, j int) bool {
if a[i].key == a[j].key {
return a[i].minTime < a[j].minTime
}
return a[i].key < a[j].key
}
func (a blocks) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func NewTSMKeyIterator(size int, fast bool, readers ...*TSMReader) (KeyIterator, error) {
var iter []*BlockIterator
for _, r := range readers {
iter = append(iter, r.BlockIterator())
}
return &tsmKeyIterator{
readers: readers,
values: map[string][]Value{},
pos: make([]int, len(readers)),
size: size,
iterators: iter,
fast: fast,
buf: make([]blocks, len(iter)),
}, nil
}
func (k *tsmKeyIterator) Next() bool {
// Any merged blocks pending?
if len(k.merged) > 0 {
k.merged = k.merged[1:]
if len(k.merged) > 0 {
return true
}
}
// Any merged values pending?
if len(k.mergedValues) > 0 {
k.merge()
if len(k.merged) > 0 || len(k.mergedValues) > 0 {
return true
}
}
// If we still have blocks from the last read, merge them
if len(k.blocks) > 0 {
k.merge()
if len(k.merged) > 0 || len(k.mergedValues) > 0 {
return true
}
}
// Read the next block from each TSM iterator
for i, v := range k.buf {
if v == nil {
iter := k.iterators[i]
if iter.Next() {
key, minTime, maxTime, _, b, err := iter.Read()
if err != nil {
k.err = err
}
// This block may have ranges of time removed from it that would
// reduce the block min and max time.
tombstones := iter.r.TombstoneRange(key)
k.buf[i] = append(k.buf[i], &block{
minTime: minTime,
maxTime: maxTime,
key: key,
b: b,
tombstones: tombstones,
readMin: math.MaxInt64,
readMax: math.MinInt64,
})
blockKey := key
for iter.PeekNext() == blockKey {
iter.Next()
key, minTime, maxTime, _, b, err := iter.Read()
if err != nil {
k.err = err
}
tombstones := iter.r.TombstoneRange(key)
k.buf[i] = append(k.buf[i], &block{
minTime: minTime,
maxTime: maxTime,
key: key,
b: b,
tombstones: tombstones,
readMin: math.MaxInt64,
readMax: math.MinInt64,
})
}
}
}
}
// Each reader could have a different key that it's currently at, need to find
// the next smallest one to keep the sort ordering.
var minKey string