tidb rule_build_key_info 源码
tidb rule_build_key_info 代码
文件路径：/planner/core/rule_build_key_info.go
// Copyright 2017 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package core
import (
"context"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/parser/ast"
"github.com/pingcap/tidb/parser/model"
"github.com/pingcap/tidb/parser/mysql"
)
type buildKeySolver struct{}
func (s *buildKeySolver) optimize(_ context.Context, p LogicalPlan, _ *logicalOptimizeOp) (LogicalPlan, error) {
buildKeyInfo(p)
return p, nil
}
// buildKeyInfo recursively calls LogicalPlan's BuildKeyInfo method.
func buildKeyInfo(lp LogicalPlan) {
for _, child := range lp.Children() {
buildKeyInfo(child)
}
childSchema := make([]*expression.Schema, len(lp.Children()))
for i, child := range lp.Children() {
childSchema[i] = child.Schema()
}
lp.BuildKeyInfo(lp.Schema(), childSchema)
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (la *LogicalAggregation) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
if la.IsPartialModeAgg() {
return
}
la.logicalSchemaProducer.BuildKeyInfo(selfSchema, childSchema)
la.buildSelfKeyInfo(selfSchema)
}
func (la *LogicalAggregation) buildSelfKeyInfo(selfSchema *expression.Schema) {
groupByCols := la.GetGroupByCols()
if len(groupByCols) == len(la.GroupByItems) && len(la.GroupByItems) > 0 {
indices := selfSchema.ColumnsIndices(groupByCols)
if indices != nil {
newKey := make([]*expression.Column, 0, len(indices))
for _, i := range indices {
newKey = append(newKey, selfSchema.Columns[i])
}
selfSchema.Keys = append(selfSchema.Keys, newKey)
}
}
if len(la.GroupByItems) == 0 {
la.maxOneRow = true
}
}
// If a condition is the form of (uniqueKey = constant) or (uniqueKey = Correlated column), it returns at most one row.
// This function will check it.
func (p *LogicalSelection) checkMaxOneRowCond(eqColIDs map[int64]struct{}, childSchema *expression.Schema) bool {
if len(eqColIDs) == 0 {
return false
}
// We check `UniqueKeys` as well since the condition is `col = con | corr`, not `col <=> con | corr`.
keys := make([]expression.KeyInfo, 0, len(childSchema.Keys)+len(childSchema.UniqueKeys))
keys = append(keys, childSchema.Keys...)
keys = append(keys, childSchema.UniqueKeys...)
var maxOneRow bool
for _, cols := range keys {
maxOneRow = true
for _, c := range cols {
if _, ok := eqColIDs[c.UniqueID]; !ok {
maxOneRow = false
break
}
}
if maxOneRow {
return true
}
}
return false
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalSelection) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
p.baseLogicalPlan.BuildKeyInfo(selfSchema, childSchema)
if p.maxOneRow {
return
}
eqCols := make(map[int64]struct{}, len(childSchema[0].Columns))
for _, cond := range p.Conditions {
if sf, ok := cond.(*expression.ScalarFunction); ok && sf.FuncName.L == ast.EQ {
for i, arg := range sf.GetArgs() {
if col, isCol := arg.(*expression.Column); isCol {
_, isCon := sf.GetArgs()[1-i].(*expression.Constant)
_, isCorCol := sf.GetArgs()[1-i].(*expression.CorrelatedColumn)
if isCon || isCorCol {
eqCols[col.UniqueID] = struct{}{}
}
break
}
}
}
}
p.maxOneRow = p.checkMaxOneRowCond(eqCols, childSchema[0])
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalLimit) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
p.logicalSchemaProducer.BuildKeyInfo(selfSchema, childSchema)
if p.Count == 1 {
p.maxOneRow = true
}
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalTopN) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
p.baseLogicalPlan.BuildKeyInfo(selfSchema, childSchema)
if p.Count == 1 {
p.maxOneRow = true
}
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalTableDual) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
p.baseLogicalPlan.BuildKeyInfo(selfSchema, childSchema)
if p.RowCount == 1 {
p.maxOneRow = true
}
}
// A bijection exists between columns of a projection's schema and this projection's Exprs.
// Sometimes we need a schema made by expr of Exprs to convert a column in child's schema to a column in this projection's Schema.
func (p *LogicalProjection) buildSchemaByExprs(selfSchema *expression.Schema) *expression.Schema {
schema := expression.NewSchema(make([]*expression.Column, 0, selfSchema.Len())...)
for _, expr := range p.Exprs {
if col, isCol := expr.(*expression.Column); isCol {
schema.Append(col)
} else {
// If the expression is not a column, we add a column to occupy the position.
schema.Append(&expression.Column{
UniqueID: p.ctx.GetSessionVars().AllocPlanColumnID(),
RetType: expr.GetType(),
})
}
}
return schema
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalProjection) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
// `LogicalProjection` use schema from `Exprs` to build key info. See `buildSchemaByExprs`.
// So call `baseLogicalPlan.BuildKeyInfo` here to avoid duplicated building key info.
p.baseLogicalPlan.BuildKeyInfo(selfSchema, childSchema)
selfSchema.Keys = nil
schema := p.buildSchemaByExprs(selfSchema)
for _, key := range childSchema[0].Keys {
indices := schema.ColumnsIndices(key)
if indices == nil {
continue
}
newKey := make([]*expression.Column, 0, len(key))
for _, i := range indices {
newKey = append(newKey, selfSchema.Columns[i])
}
selfSchema.Keys = append(selfSchema.Keys, newKey)
}
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (p *LogicalJoin) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
p.logicalSchemaProducer.BuildKeyInfo(selfSchema, childSchema)
switch p.JoinType {
case SemiJoin, LeftOuterSemiJoin, AntiSemiJoin, AntiLeftOuterSemiJoin:
selfSchema.Keys = childSchema[0].Clone().Keys
case InnerJoin, LeftOuterJoin, RightOuterJoin:
// If there is no equal conditions, then cartesian product can't be prevented and unique key information will destroy.
if len(p.EqualConditions) == 0 {
return
}
lOk := false
rOk := false
// Such as 'select * from t1 join t2 where t1.a = t2.a and t1.b = t2.b'.
// If one sides (a, b) is a unique key, then the unique key information is remained.
// But we don't consider this situation currently.
// Only key made by one column is considered now.
for _, expr := range p.EqualConditions {
ln := expr.GetArgs()[0].(*expression.Column)
rn := expr.GetArgs()[1].(*expression.Column)
for _, key := range childSchema[0].Keys {
if len(key) == 1 && key[0].Equal(p.ctx, ln) {
lOk = true
break
}
}
for _, key := range childSchema[1].Keys {
if len(key) == 1 && key[0].Equal(p.ctx, rn) {
rOk = true
break
}
}
}
// For inner join, if one side of one equal condition is unique key,
// another side's unique key information will all be reserved.
// If it's an outer join, NULL value will fill some position, which will destroy the unique key information.
if lOk && p.JoinType != LeftOuterJoin {
selfSchema.Keys = append(selfSchema.Keys, childSchema[1].Keys...)
}
if rOk && p.JoinType != RightOuterJoin {
selfSchema.Keys = append(selfSchema.Keys, childSchema[0].Keys...)
}
}
}
// checkIndexCanBeKey checks whether an Index can be a Key in schema.
func checkIndexCanBeKey(idx *model.IndexInfo, columns []*model.ColumnInfo, schema *expression.Schema) (uniqueKey, newKey expression.KeyInfo) {
if !idx.Unique {
return nil, nil
}
newKeyOK := true
uniqueKeyOK := true
for _, idxCol := range idx.Columns {
// The columns of this index should all occur in column schema.
// Since null value could be duplicate in unique key. So we check NotNull flag of every column.
findUniqueKey := false
for i, col := range columns {
if idxCol.Name.L == col.Name.L {
uniqueKey = append(uniqueKey, schema.Columns[i])
findUniqueKey = true
if newKeyOK {
if !mysql.HasNotNullFlag(col.GetFlag()) {
newKeyOK = false
break
}
newKey = append(newKey, schema.Columns[i])
break
}
}
}
if !findUniqueKey {
newKeyOK = false
uniqueKeyOK = false
break
}
}
if newKeyOK {
return nil, newKey
} else if uniqueKeyOK {
return uniqueKey, nil
}
return nil, nil
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (ds *DataSource) BuildKeyInfo(selfSchema *expression.Schema, _ []*expression.Schema) {
selfSchema.Keys = nil
var latestIndexes map[int64]*model.IndexInfo
var changed bool
var err error
check := ds.ctx.GetSessionVars().IsIsolation(ast.ReadCommitted) || ds.isForUpdateRead
check = check && ds.ctx.GetSessionVars().ConnectionID > 0
// we should check index valid while forUpdateRead, see detail in https://github.com/pingcap/tidb/pull/22152
if check {
latestIndexes, changed, err = getLatestIndexInfo(ds.ctx, ds.table.Meta().ID, 0)
if err != nil {
return
}
}
for _, index := range ds.table.Meta().Indices {
if ds.isForUpdateRead && changed {
latestIndex, ok := latestIndexes[index.ID]
if !ok || latestIndex.State != model.StatePublic {
continue
}
} else if index.State != model.StatePublic {
continue
}
if uniqueKey, newKey := checkIndexCanBeKey(index, ds.Columns, selfSchema); newKey != nil {
selfSchema.Keys = append(selfSchema.Keys, newKey)
} else if uniqueKey != nil {
selfSchema.UniqueKeys = append(selfSchema.UniqueKeys, uniqueKey)
}
}
if ds.tableInfo.PKIsHandle {
for i, col := range ds.Columns {
if mysql.HasPriKeyFlag(col.GetFlag()) {
selfSchema.Keys = append(selfSchema.Keys, []*expression.Column{selfSchema.Columns[i]})
break
}
}
}
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (ts *LogicalTableScan) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
ts.Source.BuildKeyInfo(selfSchema, childSchema)
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (is *LogicalIndexScan) BuildKeyInfo(selfSchema *expression.Schema, _ []*expression.Schema) {
selfSchema.Keys = nil
for _, path := range is.Source.possibleAccessPaths {
if path.IsTablePath() {
continue
}
if uniqueKey, newKey := checkIndexCanBeKey(path.Index, is.Columns, selfSchema); newKey != nil {
selfSchema.Keys = append(selfSchema.Keys, newKey)
} else if uniqueKey != nil {
selfSchema.UniqueKeys = append(selfSchema.UniqueKeys, uniqueKey)
}
}
handle := is.getPKIsHandleCol(selfSchema)
if handle != nil {
selfSchema.Keys = append(selfSchema.Keys, []*expression.Column{handle})
}
}
// BuildKeyInfo implements LogicalPlan BuildKeyInfo interface.
func (tg *TiKVSingleGather) BuildKeyInfo(selfSchema *expression.Schema, childSchema []*expression.Schema) {
selfSchema.Keys = childSchema[0].Keys
}
func (*buildKeySolver) name() string {
return "build_keys"
}
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