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logical_plan_builder.go
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logical_plan_builder.go
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// Copyright 2016 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package plan
import (
"fmt"
"strings"
"unicode"
"github.com/cznic/mathutil"
"github.com/juju/errors"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/expression/aggregation"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/parser"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/statistics"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/util/types"
)
const (
// TiDBMergeJoin is hint enforce merge join.
TiDBMergeJoin = "tidb_smj"
// TiDBIndexNestedLoopJoin is hint enforce index nested loop join.
TiDBIndexNestedLoopJoin = "tidb_inlj"
)
type idAllocator struct {
id int
}
func (a *idAllocator) allocID() int {
a.id++
return a.id
}
func (p *LogicalAggregation) collectGroupByColumns() {
p.groupByCols = p.groupByCols[:0]
for _, item := range p.GroupByItems {
if col, ok := item.(*expression.Column); ok {
p.groupByCols = append(p.groupByCols, col)
}
}
}
func (b *planBuilder) buildAggregation(p LogicalPlan, aggFuncList []*ast.AggregateFuncExpr, gbyItems []expression.Expression) (LogicalPlan, map[int]int) {
b.optFlag = b.optFlag | flagBuildKeyInfo
b.optFlag = b.optFlag | flagAggregationOptimize
agg := LogicalAggregation{AggFuncs: make([]aggregation.Aggregation, 0, len(aggFuncList))}.init(b.allocator, b.ctx)
schema := expression.NewSchema(make([]*expression.Column, 0, len(aggFuncList)+p.Schema().Len())...)
// aggIdxMap maps the old index to new index after applying common aggregation functions elimination.
aggIndexMap := make(map[int]int)
for i, aggFunc := range aggFuncList {
var newArgList []expression.Expression
for _, arg := range aggFunc.Args {
newArg, np, err := b.rewrite(arg, p, nil, true)
if err != nil {
b.err = errors.Trace(err)
return nil, nil
}
p = np
newArgList = append(newArgList, newArg)
}
newFunc := aggregation.NewAggFunction(aggFunc.F, newArgList, aggFunc.Distinct)
combined := false
for j, oldFunc := range agg.AggFuncs {
if oldFunc.Equal(newFunc, b.ctx) {
aggIndexMap[i] = j
combined = true
break
}
}
if !combined {
position := len(agg.AggFuncs)
aggIndexMap[i] = position
agg.AggFuncs = append(agg.AggFuncs, newFunc)
schema.Append(&expression.Column{
FromID: agg.id,
ColName: model.NewCIStr(fmt.Sprintf("%d_col_%d", agg.id, position)),
Position: position,
IsAggOrSubq: true,
RetType: newFunc.GetType()})
}
}
for _, col := range p.Schema().Columns {
newFunc := aggregation.NewAggFunction(ast.AggFuncFirstRow, []expression.Expression{col.Clone()}, false)
agg.AggFuncs = append(agg.AggFuncs, newFunc)
schema.Append(col.Clone().(*expression.Column))
}
setParentAndChildren(agg, p)
agg.GroupByItems = gbyItems
agg.SetSchema(schema)
agg.collectGroupByColumns()
return agg, aggIndexMap
}
func (b *planBuilder) buildResultSetNode(node ast.ResultSetNode) LogicalPlan {
switch x := node.(type) {
case *ast.Join:
return b.buildJoin(x)
case *ast.TableSource:
var p LogicalPlan
switch v := x.Source.(type) {
case *ast.SelectStmt:
p = b.buildSelect(v)
case *ast.UnionStmt:
p = b.buildUnion(v)
case *ast.TableName:
p = b.buildDataSource(v)
default:
b.err = ErrUnsupportedType.Gen("unsupported table source type %T", v)
return nil
}
if b.err != nil {
return nil
}
if v, ok := p.(*DataSource); ok {
v.TableAsName = &x.AsName
}
for _, col := range p.Schema().Columns {
col.OrigTblName = col.TblName
if x.AsName.L != "" {
col.TblName = x.AsName
col.DBName = model.NewCIStr("")
}
}
return p
case *ast.SelectStmt:
return b.buildSelect(x)
case *ast.UnionStmt:
return b.buildUnion(x)
default:
b.err = ErrUnsupportedType.Gen("unsupported table source type %T", x)
return nil
}
}
func extractCorColumns(expr expression.Expression) (cols []*expression.CorrelatedColumn) {
switch v := expr.(type) {
case *expression.CorrelatedColumn:
return []*expression.CorrelatedColumn{v}
case *expression.ScalarFunction:
for _, arg := range v.GetArgs() {
cols = append(cols, extractCorColumns(arg)...)
}
}
return
}
func extractOnCondition(conditions []expression.Expression, left LogicalPlan, right LogicalPlan) (
eqCond []*expression.ScalarFunction, leftCond []expression.Expression, rightCond []expression.Expression,
otherCond []expression.Expression) {
for _, expr := range conditions {
binop, ok := expr.(*expression.ScalarFunction)
if ok && binop.FuncName.L == ast.EQ {
ln, lOK := binop.GetArgs()[0].(*expression.Column)
rn, rOK := binop.GetArgs()[1].(*expression.Column)
if lOK && rOK {
if left.Schema().Contains(ln) && right.Schema().Contains(rn) {
eqCond = append(eqCond, binop)
continue
}
if left.Schema().Contains(rn) && right.Schema().Contains(ln) {
cond := expression.NewFunctionInternal(binop.GetCtx(), ast.EQ, types.NewFieldType(mysql.TypeTiny), rn, ln)
eqCond = append(eqCond, cond.(*expression.ScalarFunction))
continue
}
}
}
columns := expression.ExtractColumns(expr)
allFromLeft, allFromRight := true, true
for _, col := range columns {
if !left.Schema().Contains(col) {
allFromLeft = false
}
if !right.Schema().Contains(col) {
allFromRight = false
}
}
if allFromRight {
rightCond = append(rightCond, expr)
} else if allFromLeft {
leftCond = append(leftCond, expr)
} else {
otherCond = append(otherCond, expr)
}
}
return
}
func extractTableAlias(p LogicalPlan) *model.CIStr {
if dataSource, ok := p.(*DataSource); ok {
if dataSource.TableAsName.L != "" {
return dataSource.TableAsName
}
return &dataSource.tableInfo.Name
} else if len(p.Schema().Columns) > 0 {
if p.Schema().Columns[0].TblName.L != "" {
return &(p.Schema().Columns[0].TblName)
}
}
return nil
}
func (b *planBuilder) buildJoin(join *ast.Join) LogicalPlan {
if join.Right == nil {
return b.buildResultSetNode(join.Left)
}
b.optFlag = b.optFlag | flagPredicatePushDown
leftPlan := b.buildResultSetNode(join.Left)
rightPlan := b.buildResultSetNode(join.Right)
leftAlias := extractTableAlias(leftPlan)
rightAlias := extractTableAlias(rightPlan)
newSchema := expression.MergeSchema(leftPlan.Schema(), rightPlan.Schema())
joinPlan := LogicalJoin{}.init(b.allocator, b.ctx)
setParentAndChildren(joinPlan, leftPlan, rightPlan)
joinPlan.SetSchema(newSchema)
// Merge sub join's redundantSchema into this join plan. When handle query like
// select t2.a from (t1 join t2 using (a)) join t3 using (a);
// we can simply search in the top level join plan to find redundant column.
var lRedundant, rRedundant *expression.Schema
if left, ok := leftPlan.(*LogicalJoin); ok && left.redundantSchema != nil {
lRedundant = left.redundantSchema
}
if right, ok := rightPlan.(*LogicalJoin); ok && right.redundantSchema != nil {
rRedundant = right.redundantSchema
}
joinPlan.redundantSchema = expression.MergeSchema(lRedundant, rRedundant)
if b.TableHints() != nil {
joinPlan.preferMergeJoin = b.TableHints().ifPreferMergeJoin(leftAlias, rightAlias)
if b.TableHints().ifPreferINLJ(leftAlias) {
joinPlan.preferINLJ = joinPlan.preferINLJ | preferLeftAsOuter
}
if b.TableHints().ifPreferINLJ(rightAlias) {
joinPlan.preferINLJ = joinPlan.preferINLJ | preferRightAsOuter
}
if joinPlan.preferMergeJoin && joinPlan.preferINLJ > 0 {
b.err = errors.New("Optimizer Hints is conflict")
return nil
}
}
if join.NaturalJoin {
if err := b.buildNaturalJoin(joinPlan, leftPlan, rightPlan, join); err != nil {
b.err = err
return nil
}
} else if join.Using != nil {
if err := b.buildUsingClause(joinPlan, leftPlan, rightPlan, join); err != nil {
b.err = err
return nil
}
} else if join.On != nil {
onExpr, _, err := b.rewrite(join.On.Expr, joinPlan, nil, false)
if err != nil {
b.err = err
return nil
}
if onExpr.IsCorrelated() {
b.err = errors.New("ON condition doesn't support subqueries yet")
return nil
}
onCondition := expression.SplitCNFItems(onExpr)
joinPlan.attachOnConds(onCondition)
} else if joinPlan.JoinType == InnerJoin {
joinPlan.cartesianJoin = true
}
if join.Tp == ast.LeftJoin {
joinPlan.JoinType = LeftOuterJoin
joinPlan.DefaultValues = make([]types.Datum, rightPlan.Schema().Len())
} else if join.Tp == ast.RightJoin {
joinPlan.JoinType = RightOuterJoin
joinPlan.DefaultValues = make([]types.Datum, leftPlan.Schema().Len())
} else {
joinPlan.JoinType = InnerJoin
}
return joinPlan
}
// buildUsingClause do redundant column elimination and column ordering based on using clause.
// According to standard SQL, producing this display order:
// First, coalesced common columns of the two joined tables, in the order in which they occur in the first table.
// Second, columns unique to the first table, in order in which they occur in that table.
// Third, columns unique to the second table, in order in which they occur in that table.
func (b *planBuilder) buildUsingClause(p *LogicalJoin, leftPlan, rightPlan LogicalPlan, join *ast.Join) error {
filter := make(map[string]bool, len(join.Using))
for _, col := range join.Using {
filter[col.Name.L] = true
}
return b.coalesceCommonColumns(p, leftPlan, rightPlan, join.Tp == ast.RightJoin, filter)
}
// buildNaturalJoin build natural join output schema. It find out all the common columns
// then using the same mechanism as buildUsingClause to eliminate redundant columns and build join conditions.
// According to standard SQL, producing this display order:
// All the common columns
// Every column in the first (left) table that is not a common column
// Every column in the second (right) table that is not a common column
func (b *planBuilder) buildNaturalJoin(p *LogicalJoin, leftPlan, rightPlan LogicalPlan, join *ast.Join) error {
return b.coalesceCommonColumns(p, leftPlan, rightPlan, join.Tp == ast.RightJoin, nil)
}
// coalesceCommonColumns is used by buildUsingClause and buildNaturalJoin. The filter is used by buildUsingClause.
func (b *planBuilder) coalesceCommonColumns(p *LogicalJoin, leftPlan, rightPlan LogicalPlan, rightJoin bool, filter map[string]bool) error {
lsc := leftPlan.Schema().Clone()
rsc := rightPlan.Schema().Clone()
lColumns, rColumns := lsc.Columns, rsc.Columns
if rightJoin {
lColumns, rColumns = rsc.Columns, lsc.Columns
}
// Find out all the common columns and put them ahead.
commonLen := 0
for i, lCol := range lColumns {
for j := commonLen; j < len(rColumns); j++ {
if lCol.ColName.L != rColumns[j].ColName.L {
continue
}
if len(filter) > 0 {
if !filter[lCol.ColName.L] {
break
}
// Mark this column exist.
filter[lCol.ColName.L] = false
}
col := lColumns[i]
copy(lColumns[commonLen+1:i+1], lColumns[commonLen:i])
lColumns[commonLen] = col
col = rColumns[j]
copy(rColumns[commonLen+1:j+1], rColumns[commonLen:j])
rColumns[commonLen] = col
commonLen++
break
}
}
if len(filter) > 0 && len(filter) != commonLen {
for col, notExist := range filter {
if notExist {
return ErrUnknownColumn.GenByArgs(col, "from clause")
}
}
}
schemaCols := make([]*expression.Column, len(lColumns)+len(rColumns)-commonLen)
copy(schemaCols[:len(lColumns)], lColumns)
copy(schemaCols[len(lColumns):], rColumns[commonLen:])
conds := make([]expression.Expression, 0, commonLen)
for i := 0; i < commonLen; i++ {
lc, rc := lsc.Columns[i], rsc.Columns[i]
cond, err := expression.NewFunction(b.ctx, ast.EQ, types.NewFieldType(mysql.TypeTiny), lc, rc)
if err != nil {
return errors.Trace(err)
}
conds = append(conds, cond)
}
p.SetSchema(expression.NewSchema(schemaCols...))
p.redundantSchema = expression.MergeSchema(p.redundantSchema, expression.NewSchema(rColumns[:commonLen]...))
p.OtherConditions = append(conds, p.OtherConditions...)
return nil
}
func (b *planBuilder) buildSelection(p LogicalPlan, where ast.ExprNode, AggMapper map[*ast.AggregateFuncExpr]int) LogicalPlan {
b.optFlag = b.optFlag | flagPredicatePushDown
conditions := splitWhere(where)
expressions := make([]expression.Expression, 0, len(conditions))
selection := Selection{}.init(b.allocator, b.ctx)
for _, cond := range conditions {
expr, np, err := b.rewrite(cond, p, AggMapper, false)
if err != nil {
b.err = err
return nil
}
p = np
if expr == nil {
continue
}
cnfItems := expression.SplitCNFItems(expr)
for _, item := range cnfItems {
if con, ok := item.(*expression.Constant); ok {
ret, err := expression.EvalBool(expression.CNFExprs{con}, nil, b.ctx)
if ret || err != nil {
continue
}
}
expressions = append(expressions, item)
}
}
if len(expressions) == 0 {
return p
}
selection.Conditions = expressions
selection.SetSchema(p.Schema().Clone())
setParentAndChildren(selection, p)
return selection
}
// buildProjectionFieldNameFromColumns builds the field name, table name and database name when field expression is a column reference.
func (b *planBuilder) buildProjectionFieldNameFromColumns(field *ast.SelectField, c *expression.Column) (colName, tblName, origTblName, dbName model.CIStr) {
if astCol, ok := getInnerFromParentheses(field.Expr).(*ast.ColumnNameExpr); ok {
colName, tblName, dbName = astCol.Name.Name, astCol.Name.Table, astCol.Name.Schema
}
if field.AsName.L != "" {
colName = field.AsName
}
if tblName.L == "" {
tblName = c.TblName
}
if dbName.L == "" {
dbName = c.DBName
}
return colName, tblName, c.OrigTblName, c.DBName
}
// buildProjectionFieldNameFromExpressions builds the field name when field expression is a normal expression.
func (b *planBuilder) buildProjectionFieldNameFromExpressions(field *ast.SelectField) model.CIStr {
if agg, ok := field.Expr.(*ast.AggregateFuncExpr); ok && agg.F == ast.AggFuncFirstRow {
// When the query is select t.a from t group by a; The Column Name should be a but not t.a;
return agg.Args[0].(*ast.ColumnNameExpr).Name.Name
}
innerExpr := getInnerFromParentheses(field.Expr)
valueExpr, isValueExpr := innerExpr.(*ast.ValueExpr)
// Non-literal: Output as inputed, except that comments need to be removed.
if !isValueExpr {
return model.NewCIStr(parser.SpecFieldPattern.ReplaceAllStringFunc(field.Text(), parser.TrimComment))
}
// Literal: Need special processing
switch valueExpr.Kind() {
case types.KindString:
projName := valueExpr.GetString()
projOffset := valueExpr.GetProjectionOffset()
if projOffset >= 0 {
projName = projName[:projOffset]
}
// See #3686, #3994:
// For string literals, string content is used as column name. Non-graph initial characters are trimmed.
fieldName := strings.TrimLeftFunc(projName, func(r rune) bool {
return !unicode.IsOneOf(mysql.RangeGraph, r)
})
return model.NewCIStr(fieldName)
case types.KindNull:
// See #4053, #3685
return model.NewCIStr("NULL")
default:
// Keep as it is.
if innerExpr.Text() != "" {
return model.NewCIStr(innerExpr.Text())
}
return model.NewCIStr(field.Text())
}
}
// buildProjectionField builds the field object according to SelectField in projection.
func (b *planBuilder) buildProjectionField(id, position int, field *ast.SelectField, expr expression.Expression) *expression.Column {
var origTblName, tblName, colName, dbName model.CIStr
if c, ok := expr.(*expression.Column); ok && !c.IsAggOrSubq {
// Field is a column reference.
colName, tblName, origTblName, dbName = b.buildProjectionFieldNameFromColumns(field, c)
} else if field.AsName.L != "" {
// Field has alias.
colName = field.AsName
} else {
// Other: field is an expression.
colName = b.buildProjectionFieldNameFromExpressions(field)
}
return &expression.Column{
FromID: id,
Position: position,
TblName: tblName,
OrigTblName: origTblName,
ColName: colName,
DBName: dbName,
RetType: expr.GetType(),
}
}
// buildProjection returns a Projection plan and non-aux columns length.
func (b *planBuilder) buildProjection(p LogicalPlan, fields []*ast.SelectField, mapper map[*ast.AggregateFuncExpr]int) (LogicalPlan, int) {
b.optFlag |= flagEliminateProjection
proj := Projection{Exprs: make([]expression.Expression, 0, len(fields))}.init(b.allocator, b.ctx)
schema := expression.NewSchema(make([]*expression.Column, 0, len(fields))...)
oldLen := 0
for _, field := range fields {
newExpr, np, err := b.rewrite(field.Expr, p, mapper, true)
if err != nil {
b.err = errors.Trace(err)
return nil, oldLen
}
p = np
proj.Exprs = append(proj.Exprs, newExpr)
col := b.buildProjectionField(proj.id, schema.Len()+1, field, newExpr)
schema.Append(col)
if !field.Auxiliary {
oldLen++
}
}
proj.SetSchema(schema)
setParentAndChildren(proj, p)
return proj, oldLen
}
func (b *planBuilder) buildDistinct(child LogicalPlan, length int) LogicalPlan {
b.optFlag = b.optFlag | flagBuildKeyInfo
b.optFlag = b.optFlag | flagAggregationOptimize
agg := LogicalAggregation{
AggFuncs: make([]aggregation.Aggregation, 0, child.Schema().Len()),
GroupByItems: expression.Column2Exprs(child.Schema().Clone().Columns[:length]),
}.init(b.allocator, b.ctx)
agg.collectGroupByColumns()
for _, col := range child.Schema().Columns {
agg.AggFuncs = append(agg.AggFuncs, aggregation.NewAggFunction(ast.AggFuncFirstRow, []expression.Expression{col}, false))
}
setParentAndChildren(agg, child)
agg.SetSchema(child.Schema().Clone())
return agg
}
// joinFieldType finds the type which can carry the given types.
func joinFieldType(a, b *types.FieldType) *types.FieldType {
resultTp := types.NewFieldType(types.MergeFieldType(a.Tp, b.Tp))
resultTp.Decimal = mathutil.Max(a.Decimal, b.Decimal)
// `Flen - Decimal` is the fraction before '.'
resultTp.Flen = mathutil.Max(a.Flen-a.Decimal, b.Flen-b.Decimal) + resultTp.Decimal
resultTp.Charset = a.Charset
resultTp.Collate = a.Collate
expression.SetBinFlagOrBinStr(b, resultTp)
return resultTp
}
func (b *planBuilder) buildUnion(union *ast.UnionStmt) LogicalPlan {
u := Union{}.init(b.allocator, b.ctx)
u.children = make([]Plan, len(union.SelectList.Selects))
for i, sel := range union.SelectList.Selects {
u.children[i] = b.buildSelect(sel)
if b.err != nil {
return nil
}
}
firstSchema := u.children[0].Schema().Clone()
for i, sel := range u.children {
if firstSchema.Len() != sel.Schema().Len() {
b.err = errors.New("The used SELECT statements have a different number of columns")
return nil
}
if _, ok := sel.(*Projection); !ok {
b.optFlag |= flagEliminateProjection
proj := Projection{Exprs: expression.Column2Exprs(sel.Schema().Columns)}.init(b.allocator, b.ctx)
schema := sel.Schema().Clone()
for _, col := range schema.Columns {
col.FromID = proj.ID()
}
proj.SetSchema(schema)
setParentAndChildren(proj, sel)
sel = proj
u.children[i] = proj
}
sel.SetParents(u)
}
// infer union type
for i, col := range firstSchema.Columns {
var resultTp *types.FieldType
for j, child := range u.children {
childTp := child.Schema().Columns[i].RetType
if j == 0 {
resultTp = childTp
} else {
resultTp = joinFieldType(resultTp, childTp)
}
}
col.RetType = resultTp
}
for _, v := range firstSchema.Columns {
v.FromID = u.id
v.DBName = model.NewCIStr("")
}
u.SetSchema(firstSchema)
var p LogicalPlan = u
if union.Distinct {
p = b.buildDistinct(u, u.Schema().Len())
}
if union.OrderBy != nil {
p = b.buildSort(p, union.OrderBy.Items, nil)
}
if union.Limit != nil {
p = b.buildLimit(p, union.Limit)
}
return p
}
// ByItems wraps a "by" item.
type ByItems struct {
Expr expression.Expression
Desc bool
}
// String implements fmt.Stringer interface.
func (by *ByItems) String() string {
if by.Desc {
return fmt.Sprintf("%s true", by.Expr)
}
return by.Expr.String()
}
// Clone makes a copy of ByItems.
func (by *ByItems) Clone() *ByItems {
return &ByItems{Expr: by.Expr.Clone(), Desc: by.Desc}
}
func (b *planBuilder) buildSort(p LogicalPlan, byItems []*ast.ByItem, aggMapper map[*ast.AggregateFuncExpr]int) LogicalPlan {
sort := Sort{}.init(b.allocator, b.ctx)
exprs := make([]*ByItems, 0, len(byItems))
for _, item := range byItems {
it, np, err := b.rewrite(item.Expr, p, aggMapper, true)
if err != nil {
b.err = err
return nil
}
p = np
exprs = append(exprs, &ByItems{Expr: it, Desc: item.Desc})
}
sort.ByItems = exprs
setParentAndChildren(sort, p)
sort.SetSchema(p.Schema().Clone())
return sort
}
// getUintForLimitOffset gets uint64 value for limit/offset.
// For ordinary statement, limit/offset should be uint64 constant value.
// For prepared statement, limit/offset is string. We should convert it to uint64.
func getUintForLimitOffset(sc *variable.StatementContext, val interface{}) (uint64, error) {
switch v := val.(type) {
case uint64:
return v, nil
case int64:
if v >= 0 {
return uint64(v), nil
}
case string:
uVal, err := types.StrToUint(sc, v)
return uVal, errors.Trace(err)
}
return 0, errors.Errorf("Invalid type %T for Limit/Offset", val)
}
func (b *planBuilder) buildLimit(src LogicalPlan, limit *ast.Limit) LogicalPlan {
if UseDAGPlanBuilder(b.ctx) {
b.optFlag = b.optFlag | flagPushDownTopN
}
var (
offset, count uint64
err error
)
sc := b.ctx.GetSessionVars().StmtCtx
if limit.Offset != nil {
offset, err = getUintForLimitOffset(sc, limit.Offset.GetValue())
if err != nil {
b.err = ErrWrongArguments
return nil
}
}
if limit.Count != nil {
count, err = getUintForLimitOffset(sc, limit.Count.GetValue())
if err != nil {
b.err = ErrWrongArguments
return nil
}
}
li := Limit{
Offset: offset,
Count: count,
}.init(b.allocator, b.ctx)
setParentAndChildren(li, src)
li.SetSchema(src.Schema().Clone())
return li
}
// colMatch(a,b) means that if a match b, e.g. t.a can match test.t.a but test.t.a can't match t.a.
// Because column a want column from database test exactly.
func colMatch(a *ast.ColumnName, b *ast.ColumnName) bool {
if a.Schema.L == "" || a.Schema.L == b.Schema.L {
if a.Table.L == "" || a.Table.L == b.Table.L {
return a.Name.L == b.Name.L
}
}
return false
}
func matchField(f *ast.SelectField, col *ast.ColumnNameExpr, ignoreAsName bool) bool {
// if col specify a table name, resolve from table source directly.
if col.Name.Table.L == "" {
if f.AsName.L == "" || ignoreAsName {
if curCol, isCol := f.Expr.(*ast.ColumnNameExpr); isCol {
return curCol.Name.Name.L == col.Name.Name.L
}
// a expression without as name can't be matched.
return false
}
return f.AsName.L == col.Name.Name.L
}
return false
}
func resolveFromSelectFields(v *ast.ColumnNameExpr, fields []*ast.SelectField, ignoreAsName bool) (index int, err error) {
var matchedExpr ast.ExprNode
index = -1
for i, field := range fields {
if field.Auxiliary {
continue
}
if matchField(field, v, ignoreAsName) {
curCol, isCol := field.Expr.(*ast.ColumnNameExpr)
if !isCol {
return i, nil
}
if matchedExpr == nil {
matchedExpr = curCol
index = i
} else if !colMatch(matchedExpr.(*ast.ColumnNameExpr).Name, curCol.Name) &&
!colMatch(curCol.Name, matchedExpr.(*ast.ColumnNameExpr).Name) {
return -1, ErrAmbiguous.GenByArgs(curCol.Name.Name.L)
}
}
}
return
}
// AggregateFuncExtractor visits Expr tree.
// It converts ColunmNameExpr to AggregateFuncExpr and collects AggregateFuncExpr.
type havingAndOrderbyExprResolver struct {
inAggFunc bool
inExpr bool
orderBy bool
err error
p LogicalPlan
selectFields []*ast.SelectField
aggMapper map[*ast.AggregateFuncExpr]int
colMapper map[*ast.ColumnNameExpr]int
gbyItems []*ast.ByItem
outerSchemas []*expression.Schema
}
// Enter implements Visitor interface.
func (a *havingAndOrderbyExprResolver) Enter(n ast.Node) (node ast.Node, skipChildren bool) {
switch n.(type) {
case *ast.AggregateFuncExpr:
a.inAggFunc = true
case *ast.ParamMarkerExpr, *ast.ColumnNameExpr, *ast.ColumnName:
case *ast.SubqueryExpr, *ast.ExistsSubqueryExpr:
// Enter a new context, skip it.
// For example: select sum(c) + c + exists(select c from t) from t;
return n, true
default:
a.inExpr = true
}
return n, false
}
func (a *havingAndOrderbyExprResolver) resolveFromSchema(v *ast.ColumnNameExpr, schema *expression.Schema) (int, error) {
col, err := schema.FindColumn(v.Name)
if err != nil {
return -1, errors.Trace(err)
}
if col == nil {
return -1, nil
}
newColName := &ast.ColumnName{
Schema: col.DBName,
Table: col.TblName,
Name: col.ColName,
}
for i, field := range a.selectFields {
if c, ok := field.Expr.(*ast.ColumnNameExpr); ok && colMatch(newColName, c.Name) {
return i, nil
}
}
sf := &ast.SelectField{
Expr: &ast.ColumnNameExpr{Name: newColName},
Auxiliary: true,
}
sf.Expr.SetType(col.GetType())
a.selectFields = append(a.selectFields, sf)
return len(a.selectFields) - 1, nil
}
// Leave implements Visitor interface.
func (a *havingAndOrderbyExprResolver) Leave(n ast.Node) (node ast.Node, ok bool) {
switch v := n.(type) {
case *ast.AggregateFuncExpr:
a.inAggFunc = false
a.aggMapper[v] = len(a.selectFields)
a.selectFields = append(a.selectFields, &ast.SelectField{
Auxiliary: true,
Expr: v,
AsName: model.NewCIStr(fmt.Sprintf("sel_agg_%d", len(a.selectFields))),
})
case *ast.ColumnNameExpr:
resolveFieldsFirst := true
if a.inAggFunc || (a.orderBy && a.inExpr) {
resolveFieldsFirst = false
}
if !a.inAggFunc && !a.orderBy {
for _, item := range a.gbyItems {
if col, ok := item.Expr.(*ast.ColumnNameExpr); ok &&
(colMatch(v.Name, col.Name) || colMatch(col.Name, v.Name)) {
resolveFieldsFirst = false
break
}
}
}
index := -1
if resolveFieldsFirst {
index, a.err = resolveFromSelectFields(v, a.selectFields, false)
if a.err != nil {
return node, false
}
if index == -1 {
if a.orderBy {
index, a.err = a.resolveFromSchema(v, a.p.Schema())
} else {
index, a.err = resolveFromSelectFields(v, a.selectFields, true)
}
}
} else {
// We should ignore the err when resolving from schema. Because we could resolve successfully
// when considering select fields.
var err error
index, err = a.resolveFromSchema(v, a.p.Schema())
_ = err
if index == -1 {
index, a.err = resolveFromSelectFields(v, a.selectFields, false)
}
}
if a.err != nil {
return node, false
}
if index == -1 {
// If we can't find it any where, it may be a correlated columns.
for _, schema := range a.outerSchemas {
col, err1 := schema.FindColumn(v.Name)
if err1 != nil {
a.err = errors.Trace(err1)
return node, false
}
if col != nil {
return n, true
}
}
a.err = errors.Errorf("Unknown Column %s", v.Name.Name.L)
return node, false
}
if a.inAggFunc {
return a.selectFields[index].Expr, true
}
a.colMapper[v] = index
}
return n, true
}
// resolveHavingAndOrderBy will process aggregate functions and resolve the columns that don't exist in select fields.
// If we found some columns that are not in select fields, we will append it to select fields and update the colMapper.
// When we rewrite the order by / having expression, we will find column in map at first.
func (b *planBuilder) resolveHavingAndOrderBy(sel *ast.SelectStmt, p LogicalPlan) (
map[*ast.AggregateFuncExpr]int, map[*ast.AggregateFuncExpr]int) {
extractor := &havingAndOrderbyExprResolver{
p: p,
selectFields: sel.Fields.Fields,
aggMapper: make(map[*ast.AggregateFuncExpr]int),
colMapper: b.colMapper,
outerSchemas: b.outerSchemas,
}
if sel.GroupBy != nil {
extractor.gbyItems = sel.GroupBy.Items
}
// Extract agg funcs from having clause.
if sel.Having != nil {
n, ok := sel.Having.Expr.Accept(extractor)
if !ok {
b.err = errors.Trace(extractor.err)
return nil, nil
}
sel.Having.Expr = n.(ast.ExprNode)
}
havingAggMapper := extractor.aggMapper
extractor.aggMapper = make(map[*ast.AggregateFuncExpr]int)
extractor.orderBy = true
extractor.inExpr = false
// Extract agg funcs from order by clause.
if sel.OrderBy != nil {
for _, item := range sel.OrderBy.Items {
n, ok := item.Expr.Accept(extractor)
if !ok {
b.err = errors.Trace(extractor.err)
return nil, nil
}
item.Expr = n.(ast.ExprNode)
}
}
sel.Fields.Fields = extractor.selectFields
return havingAggMapper, extractor.aggMapper
}
func (b *planBuilder) extractAggFuncs(fields []*ast.SelectField) ([]*ast.AggregateFuncExpr, map[*ast.AggregateFuncExpr]int) {
extractor := &AggregateFuncExtractor{}
for _, f := range fields {
n, _ := f.Expr.Accept(extractor)
f.Expr = n.(ast.ExprNode)
}
aggList := extractor.AggFuncs
totalAggMapper := make(map[*ast.AggregateFuncExpr]int)
for i, agg := range aggList {
totalAggMapper[agg] = i
}
return aggList, totalAggMapper
}
// gbyResolver resolves group by items from select fields.
type gbyResolver struct {
fields []*ast.SelectField
schema *expression.Schema
err error
inExpr bool
}
func (g *gbyResolver) Enter(inNode ast.Node) (ast.Node, bool) {
switch inNode.(type) {
case *ast.SubqueryExpr, *ast.CompareSubqueryExpr, *ast.ExistsSubqueryExpr:
return inNode, true
case *ast.ValueExpr, *ast.ColumnNameExpr, *ast.ParenthesesExpr, *ast.ColumnName:
default:
g.inExpr = true
}
return inNode, false
}
func (g *gbyResolver) Leave(inNode ast.Node) (ast.Node, bool) {
switch v := inNode.(type) {
case *ast.ColumnNameExpr:
col, err := g.schema.FindColumn(v.Name)
if col == nil || !g.inExpr {
var index = -1
index, g.err = resolveFromSelectFields(v, g.fields, false)
if g.err != nil {
return inNode, false
}
if col != nil {
return inNode, true
}
if index != -1 {
return g.fields[index].Expr, true
}
g.err = errors.Trace(err)
return inNode, false
}
case *ast.PositionExpr:
if v.N >= 1 && v.N <= len(g.fields) {
return g.fields[v.N-1].Expr, true
}
g.err = errors.Errorf("Unknown column '%d' in 'group statement'", v.N)
return inNode, false
}
return inNode, true
}