3b25069f84
* evaluator: avoid evaluate independent subquery multiple times. * ast: rename UseOuterContext to Correlated.
154 lines
3.3 KiB
Go
154 lines
3.3 KiB
Go
// Copyright 2015 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 executor
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import (
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"github.com/juju/errors"
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"github.com/pingcap/tidb/ast"
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"github.com/pingcap/tidb/context"
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"github.com/pingcap/tidb/evaluator"
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"github.com/pingcap/tidb/infoschema"
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"github.com/pingcap/tidb/optimizer/plan"
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)
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// recordSet wraps an executor, implements ast.RecordSet interface
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type recordSet struct {
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fields []*ast.ResultField
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executor Executor
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}
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func (a *recordSet) Fields() ([]*ast.ResultField, error) {
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return a.fields, nil
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}
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func (a *recordSet) Next() (*ast.Row, error) {
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row, err := a.executor.Next()
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if err != nil || row == nil {
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return nil, errors.Trace(err)
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}
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return &ast.Row{Data: row.Data}, nil
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}
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func (a *recordSet) Close() error {
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return a.executor.Close()
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}
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type statement struct {
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is infoschema.InfoSchema
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plan plan.Plan
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node ast.Node
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}
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func (a *statement) OriginText() string {
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return ""
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}
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func (a *statement) SetText(text string) {
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return
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}
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func (a *statement) IsDDL() bool {
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return false
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}
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func (a *statement) Exec(ctx context.Context) (ast.RecordSet, error) {
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b := newExecutorBuilder(ctx, a.is)
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e := b.build(a.plan)
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if b.err != nil {
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return nil, errors.Trace(b.err)
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}
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if executorExec, ok := e.(*ExecuteExec); ok {
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err := executorExec.Build()
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if err != nil {
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return nil, errors.Trace(err)
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}
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e = executorExec.StmtExec
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a.node = executorExec.Stmt
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}
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// Execute independent subquery.
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subExec := &subqueryExecutor{ctx: ctx}
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a.node.Accept(subExec)
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if subExec.err != nil {
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return nil, errors.Trace(subExec.err)
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}
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if len(e.Fields()) == 0 {
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// No result fields means no Recordset.
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defer e.Close()
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for {
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row, err := e.Next()
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if err != nil {
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return nil, errors.Trace(err)
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}
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if row == nil {
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return nil, nil
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}
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}
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}
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fs := e.Fields()
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for _, f := range fs {
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if len(f.ColumnAsName.O) == 0 {
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f.ColumnAsName = f.Column.Name
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}
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}
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return &recordSet{
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executor: e,
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fields: fs,
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}, nil
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}
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// subqueryExecutor executes independent subquery.
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type subqueryExecutor struct {
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ctx context.Context
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multipleRows bool
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existRow bool
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err error
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}
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func (e *subqueryExecutor) Enter(in ast.Node) (ast.Node, bool) {
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switch in.(type) {
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case *ast.ExistsSubqueryExpr:
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e.existRow = true
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case *ast.CompareSubqueryExpr:
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e.multipleRows = true
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case *ast.PatternInExpr:
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e.multipleRows = true
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}
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return in, false
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}
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func (e *subqueryExecutor) Leave(in ast.Node) (ast.Node, bool) {
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switch x := in.(type) {
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case *ast.CompareSubqueryExpr:
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e.multipleRows = false
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case *ast.PatternInExpr:
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e.multipleRows = false
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case *ast.ExistsSubqueryExpr:
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e.existRow = false
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case *ast.SubqueryExpr:
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if !x.Correlated {
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err := evaluator.EvalSubquery(e.ctx, x, e.multipleRows, e.existRow)
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if err != nil {
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e.err = errors.Trace(err)
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return in, false
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}
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return in, true
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}
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}
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return in, true
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}
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