252 lines
8.2 KiB
Go
252 lines
8.2 KiB
Go
// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package plan
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import (
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"github.com/ngaut/log"
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"github.com/pingcap/tidb/ast"
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"github.com/pingcap/tidb/expression"
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)
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func getUsedList(usedCols []*expression.Column, schema expression.Schema) []bool {
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used := make([]bool, len(schema))
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for _, col := range usedCols {
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idx := schema.GetIndex(col)
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if idx == -1 {
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log.Errorf("Can't find column %s from schema %s.", col, schema)
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}
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used[idx] = true
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}
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return used
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}
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// exprHasSetVar checks if the expression has set-var function. If do, we should not prune it.
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func exprHasSetVar(expr expression.Expression) bool {
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if fun, ok := expr.(*expression.ScalarFunction); ok {
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canPrune := true
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if fun.FuncName.L == ast.SetVar {
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return false
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}
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for _, arg := range fun.Args {
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canPrune = canPrune && exprHasSetVar(arg)
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if !canPrune {
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return false
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}
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}
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}
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return true
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Projection) PruneColumns(parentUsedCols []*expression.Column) {
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child := p.GetChildByIndex(0).(LogicalPlan)
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var selfUsedCols []*expression.Column
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used := getUsedList(parentUsedCols, p.schema)
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for i := len(used) - 1; i >= 0; i-- {
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if !used[i] && exprHasSetVar(p.Exprs[i]) {
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p.schema = append(p.schema[:i], p.schema[i+1:]...)
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p.Exprs = append(p.Exprs[:i], p.Exprs[i+1:]...)
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}
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}
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for _, expr := range p.Exprs {
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selfUsedCols = append(selfUsedCols, expression.ExtractColumns(expr)...)
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}
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child.PruneColumns(selfUsedCols)
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Selection) PruneColumns(parentUsedCols []*expression.Column) {
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child := p.GetChildByIndex(0).(LogicalPlan)
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for _, cond := range p.Conditions {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(cond)...)
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}
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child.PruneColumns(parentUsedCols)
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p.SetSchema(child.GetSchema())
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Aggregation) PruneColumns(parentUsedCols []*expression.Column) {
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child := p.GetChildByIndex(0).(LogicalPlan)
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used := getUsedList(parentUsedCols, p.schema)
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for i := len(used) - 1; i >= 0; i-- {
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if !used[i] {
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p.schema = append(p.schema[:i], p.schema[i+1:]...)
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p.AggFuncs = append(p.AggFuncs[:i], p.AggFuncs[i+1:]...)
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}
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}
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var selfUsedCols []*expression.Column
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for _, aggrFunc := range p.AggFuncs {
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for _, arg := range aggrFunc.GetArgs() {
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selfUsedCols = append(selfUsedCols, expression.ExtractColumns(arg)...)
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}
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}
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for _, expr := range p.GroupByItems {
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selfUsedCols = append(selfUsedCols, expression.ExtractColumns(expr)...)
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}
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child.PruneColumns(selfUsedCols)
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Sort) PruneColumns(parentUsedCols []*expression.Column) {
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child := p.GetChildByIndex(0).(LogicalPlan)
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for _, item := range p.ByItems {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(item.Expr)...)
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}
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child.PruneColumns(parentUsedCols)
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p.SetSchema(p.GetChildByIndex(0).GetSchema())
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Union) PruneColumns(parentUsedCols []*expression.Column) {
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used := getUsedList(parentUsedCols, p.GetSchema())
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for i := len(used) - 1; i >= 0; i-- {
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if !used[i] {
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p.schema = append(p.schema[:i], p.schema[i+1:]...)
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}
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}
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for _, c := range p.GetChildren() {
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child := c.(LogicalPlan)
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schema := child.GetSchema()
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var newSchema []*expression.Column
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for i, use := range used {
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if use {
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newSchema = append(newSchema, schema[i])
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}
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}
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child.PruneColumns(newSchema)
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}
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *DataSource) PruneColumns(parentUsedCols []*expression.Column) {
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used := getUsedList(parentUsedCols, p.schema)
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for i := len(used) - 1; i >= 0; i-- {
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if !used[i] {
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p.schema = append(p.schema[:i], p.schema[i+1:]...)
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p.Columns = append(p.Columns[:i], p.Columns[i+1:]...)
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}
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}
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *TableDual) PruneColumns(_ []*expression.Column) {
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Trim) PruneColumns(parentUsedCols []*expression.Column) {
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used := getUsedList(parentUsedCols, p.schema)
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for i := len(used) - 1; i >= 0; i-- {
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if !used[i] {
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p.schema = append(p.schema[:i], p.schema[i+1:]...)
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}
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}
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p.GetChildByIndex(0).(LogicalPlan).PruneColumns(parentUsedCols)
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Exists) PruneColumns(parentUsedCols []*expression.Column) {
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p.GetChildByIndex(0).(LogicalPlan).PruneColumns(nil)
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Insert) PruneColumns(_ []*expression.Column) {
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if len(p.GetChildren()) == 0 {
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return
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}
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child := p.GetChildByIndex(0).(LogicalPlan)
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child.PruneColumns(child.GetSchema())
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Join) PruneColumns(parentUsedCols []*expression.Column) {
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for _, eqCond := range p.EqualConditions {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(eqCond)...)
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}
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for _, leftCond := range p.LeftConditions {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(leftCond)...)
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}
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for _, rightCond := range p.RightConditions {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(rightCond)...)
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}
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for _, otherCond := range p.OtherConditions {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(otherCond)...)
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}
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lChild := p.GetChildByIndex(0).(LogicalPlan)
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rChild := p.GetChildByIndex(1).(LogicalPlan)
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var leftCols, rightCols []*expression.Column
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for _, col := range parentUsedCols {
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if lChild.GetSchema().GetIndex(col) != -1 {
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leftCols = append(leftCols, col)
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} else if rChild.GetSchema().GetIndex(col) != -1 {
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rightCols = append(rightCols, col)
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}
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}
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lChild.PruneColumns(leftCols)
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rChild.PruneColumns(rightCols)
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composedSchema := append(lChild.GetSchema().Clone(), rChild.GetSchema().Clone()...)
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if p.JoinType == SemiJoin {
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p.schema = lChild.GetSchema().Clone()
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} else if p.JoinType == SemiJoinWithAux {
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p.schema = append(lChild.GetSchema().Clone(), p.schema[len(p.schema)-1])
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} else {
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p.schema = composedSchema
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}
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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// e.g. For query select b.c, (select count(*) from a where a.id = b.id) from b. Its plan is Projection->Apply->TableScan.
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// The schema of b is (a,b,c,id). When Pruning Apply, the parentUsedCols is (c, extra), outerSchema is (a,b,c,id).
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// Then after pruning inner plan, the childOuterUsedCols schema in apply becomes (id).
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// Now there're two columns in parentUsedCols, c is the column from Apply's child ---- TableScan, but extra isn't.
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// So only c in parentUsedCols and id in outerSchema can be passed to TableScan.
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func (p *Apply) PruneColumns(parentUsedCols []*expression.Column) {
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child := p.GetChildByIndex(0).(LogicalPlan)
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innerPlan := p.GetChildByIndex(1).(LogicalPlan)
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var usedCols []*expression.Column
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if p.Checker != nil {
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parentUsedCols = append(parentUsedCols, expression.ExtractColumns(p.Checker.Condition)...)
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}
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for _, col := range parentUsedCols {
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if child.GetSchema().GetIndex(col) != -1 {
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usedCols = append(usedCols, col)
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}
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}
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innerPlan.PruneColumns(innerPlan.GetSchema())
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corCols := innerPlan.extractCorrelatedCols()
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for _, corCol := range corCols {
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idx := child.GetSchema().GetIndex(&corCol.Column)
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if idx != -1 {
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usedCols = append(usedCols, &corCol.Column)
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}
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}
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child.PruneColumns(usedCols)
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combinedSchema := append(child.GetSchema().Clone(), innerPlan.GetSchema().Clone()...)
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if p.Checker == nil {
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p.schema = combinedSchema
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} else {
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p.schema = append(child.GetSchema().Clone(), p.schema[len(p.schema)-1])
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}
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p.schema.InitIndices()
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}
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// PruneColumns implements LogicalPlan interface.
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func (p *Update) PruneColumns(parentUsedCols []*expression.Column) {
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p.baseLogicalPlan.PruneColumns(p.GetChildByIndex(0).GetSchema())
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}
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