-
Notifications
You must be signed in to change notification settings - Fork 5.8k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
planner: support join elimination rule (#8021)
- Loading branch information
Showing
6 changed files
with
282 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,192 @@ | ||
| // Copyright 2018 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 core | ||
|
|
||
| import ( | ||
| "github.com/pingcap/parser/ast" | ||
| "github.com/pingcap/tidb/expression" | ||
| ) | ||
|
|
||
| type outerJoinEliminator struct { | ||
| } | ||
|
|
||
| // tryToEliminateOuterJoin will eliminate outer join plan base on the following rules | ||
| // 1. outer join elimination: For example left outer join, if the parent only use the | ||
| // columns from left table and the join key of right table(the inner table) is a unique | ||
| // key of the right table. the left outer join can be eliminated. | ||
| // 2. outer join elimination with duplicate agnostic aggregate functions: For example left outer join. | ||
| // If the parent only use the columns from left table with 'distinct' label. The left outer join can | ||
| // be eliminated. | ||
| func (o *outerJoinEliminator) tryToEliminateOuterJoin(p *LogicalJoin, aggCols []*expression.Column, parentSchema *expression.Schema) LogicalPlan { | ||
| var innerChildIdx int | ||
| switch p.JoinType { | ||
| case LeftOuterJoin: | ||
| innerChildIdx = 1 | ||
| case RightOuterJoin: | ||
| innerChildIdx = 0 | ||
| default: | ||
| return p | ||
| } | ||
|
|
||
| outerPlan := p.children[1^innerChildIdx] | ||
| innerPlan := p.children[innerChildIdx] | ||
| // outer join elimination with duplicate agnostic aggregate functions | ||
| if o.isAggColsAllFromOuterTable(outerPlan, aggCols) { | ||
| return outerPlan | ||
| } | ||
| // outer join elimination without duplicate agnostic aggregate functions | ||
| if !o.isParentColsAllFromOuterTable(outerPlan, parentSchema) { | ||
| return p | ||
| } | ||
| innerJoinKeys := o.extractInnerJoinKeys(p, innerChildIdx) | ||
| if o.isInnerJoinKeysContainUniqueKey(innerPlan, innerJoinKeys) { | ||
| return outerPlan | ||
| } | ||
| if o.isInnerJoinKeysContainIndex(innerPlan, innerJoinKeys) { | ||
| return outerPlan | ||
| } | ||
| return p | ||
| } | ||
|
|
||
| // extract join keys as a schema for inner child of a outer join | ||
| func (o *outerJoinEliminator) extractInnerJoinKeys(join *LogicalJoin, innerChildIdx int) *expression.Schema { | ||
| var joinKeys []*expression.Column | ||
| for _, eqCond := range join.EqualConditions { | ||
| joinKeys = append(joinKeys, eqCond.GetArgs()[innerChildIdx].(*expression.Column)) | ||
| } | ||
| return expression.NewSchema(joinKeys...) | ||
| } | ||
|
|
||
| func (o *outerJoinEliminator) isAggColsAllFromOuterTable(outerPlan LogicalPlan, aggCols []*expression.Column) bool { | ||
| if len(aggCols) == 0 { | ||
| return false | ||
| } | ||
| for _, col := range aggCols { | ||
| columnName := &ast.ColumnName{Schema: col.DBName, Table: col.TblName, Name: col.ColName} | ||
| if c, _ := outerPlan.Schema().FindColumn(columnName); c == nil { | ||
| return false | ||
| } | ||
| } | ||
| return true | ||
| } | ||
|
|
||
| // check whether schema cols of join's parent plan are all from outer join table | ||
| func (o *outerJoinEliminator) isParentColsAllFromOuterTable(outerPlan LogicalPlan, parentSchema *expression.Schema) bool { | ||
| if parentSchema == nil { | ||
| return false | ||
| } | ||
| for _, col := range parentSchema.Columns { | ||
| columnName := &ast.ColumnName{Schema: col.DBName, Table: col.TblName, Name: col.ColName} | ||
| if c, _ := outerPlan.Schema().FindColumn(columnName); c == nil { | ||
| return false | ||
| } | ||
| } | ||
| return true | ||
| } | ||
|
|
||
| // check whether one of unique keys sets is contained by inner join keys | ||
| func (o *outerJoinEliminator) isInnerJoinKeysContainUniqueKey(innerPlan LogicalPlan, joinKeys *expression.Schema) bool { | ||
| for _, keyInfo := range innerPlan.Schema().Keys { | ||
| joinKeysContainKeyInfo := true | ||
| for _, col := range keyInfo { | ||
| columnName := &ast.ColumnName{Schema: col.DBName, Table: col.TblName, Name: col.ColName} | ||
| if c, _ := joinKeys.FindColumn(columnName); c == nil { | ||
| joinKeysContainKeyInfo = false | ||
| break | ||
| } | ||
| } | ||
| if joinKeysContainKeyInfo { | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
|
||
| // check whether one of index sets is contained by inner join index | ||
| func (o *outerJoinEliminator) isInnerJoinKeysContainIndex(innerPlan LogicalPlan, joinKeys *expression.Schema) bool { | ||
| ds, ok := innerPlan.(*DataSource) | ||
| if !ok { | ||
| return false | ||
| } | ||
| for _, path := range ds.possibleAccessPaths { | ||
| if path.isTablePath { | ||
| continue | ||
| } | ||
| idx := path.index | ||
| if !idx.Unique { | ||
| continue | ||
| } | ||
| joinKeysContainIndex := true | ||
| for _, idxCol := range idx.Columns { | ||
| columnName := &ast.ColumnName{Schema: ds.DBName, Table: ds.tableInfo.Name, Name: idxCol.Name} | ||
| if c, _ := joinKeys.FindColumn(columnName); c == nil { | ||
| joinKeysContainIndex = false | ||
| break | ||
| } | ||
| } | ||
| if joinKeysContainIndex { | ||
| return true | ||
| } | ||
| } | ||
| return false | ||
| } | ||
|
|
||
| // Check whether a LogicalPlan is a LogicalAggregation and its all aggregate functions is duplicate agnostic. | ||
| // Also, check all the args are expression.Column. | ||
| func (o *outerJoinEliminator) isDuplicateAgnosticAgg(p LogicalPlan) (_ bool, cols []*expression.Column) { | ||
| agg, ok := p.(*LogicalAggregation) | ||
| if !ok { | ||
| return false, nil | ||
| } | ||
| cols = agg.groupByCols | ||
| for _, aggDesc := range agg.AggFuncs { | ||
| if !aggDesc.HasDistinct && | ||
| aggDesc.Name != ast.AggFuncFirstRow && | ||
| aggDesc.Name != ast.AggFuncMax && | ||
| aggDesc.Name != ast.AggFuncMin { | ||
| return false, nil | ||
| } | ||
| for _, expr := range aggDesc.Args { | ||
| if col, ok := expr.(*expression.Column); ok { | ||
| cols = append(cols, col) | ||
| } else { | ||
| return false, nil | ||
| } | ||
| } | ||
| } | ||
| return true, cols | ||
| } | ||
|
|
||
| func (o *outerJoinEliminator) doOptimize(p LogicalPlan, aggCols []*expression.Column, parentSchema *expression.Schema) LogicalPlan { | ||
| // check the duplicate agnostic aggregate functions | ||
| if ok, newCols := o.isDuplicateAgnosticAgg(p); ok { | ||
| aggCols = newCols | ||
| } | ||
|
|
||
| newChildren := make([]LogicalPlan, 0, len(p.Children())) | ||
| for _, child := range p.Children() { | ||
| newChild := o.doOptimize(child, aggCols, p.Schema()) | ||
| newChildren = append(newChildren, newChild) | ||
| } | ||
| p.SetChildren(newChildren...) | ||
| join, isJoin := p.(*LogicalJoin) | ||
| if !isJoin { | ||
| return p | ||
| } | ||
| return o.tryToEliminateOuterJoin(join, aggCols, parentSchema) | ||
| } | ||
|
|
||
| func (o *outerJoinEliminator) optimize(p LogicalPlan) (LogicalPlan, error) { | ||
| return o.doOptimize(p, nil, nil), nil | ||
| } |