d97f091cb7
The position expression, like "1" in "order by 1" was parsed ito `*ast.ValueExpr` in parser, replaced to position expression by resolver, But flag setter sets flag before resolving process, so position flag is not set.
547 lines
16 KiB
Go
547 lines
16 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 optimizer
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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/infoschema"
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"github.com/pingcap/tidb/model"
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"github.com/pingcap/tidb/sessionctx/db"
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)
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// ResolveName resolves table name and column name.
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// It generates ResultFields for ResetSetNode and resolve ColumnNameExpr to a ResultField.
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func ResolveName(node ast.Node, info infoschema.InfoSchema, ctx context.Context) error {
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defaultSchema := db.GetCurrentSchema(ctx)
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resolver := nameResolver{Info: info, Ctx: ctx, DefaultSchema: model.NewCIStr(defaultSchema)}
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node.Accept(&resolver)
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return resolver.Err
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}
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// nameResolver is the visitor to resolve table name and column name.
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// In general, a reference can only refer to information that are available for it.
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// So children elements are visited in the order that previous elements make information
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// available for following elements.
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//
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// During visiting, information are collected and stored in resolverContext.
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// When we enter a subquery, a new resolverContext is pushed to the contextStack, so sub query
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// information can overwrite outer query information. When we look up for a column reference,
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// we look up from top to bottom in the contextStack.
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type nameResolver struct {
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Info infoschema.InfoSchema
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Ctx context.Context
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DefaultSchema model.CIStr
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Err error
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contextStack []*resolverContext
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}
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// resolverContext stores information in a single level of select statement
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// that table name and column name can be resolved.
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type resolverContext struct {
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/* For Select Statement. */
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// table map to lookup and check table name conflict.
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tableMap map[string]int
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// tableSources collected in from clause.
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tables []*ast.TableSource
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// result fields collected in select field list.
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fieldList []*ast.ResultField
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// result fields collected in group by clause.
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groupBy []*ast.ResultField
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// The join node stack is used by on condition to find out
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// available tables to reference. On condition can only
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// refer to tables involved in current join.
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joinNodeStack []*ast.Join
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// When visiting TableRefs, tables in this context are not available
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// because it is being collected.
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inTableRefs bool
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// When visiting on conditon only tables in current join node are available.
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inOnCondition bool
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// When visiting field list, fieldList in this context are not available.
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inFieldList bool
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// When visiting group by, groupBy fields are not available.
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inGroupBy bool
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// When visiting having, only fieldList and groupBy fields are available.
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inHaving bool
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// OrderBy clause has different resolving rule than group by.
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inOrderBy bool
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// When visiting column name in ByItem, we should know if the column name is in an expression.
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inByItemExpression bool
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}
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// currentContext gets the current resolverContext.
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func (nr *nameResolver) currentContext() *resolverContext {
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stackLen := len(nr.contextStack)
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if stackLen == 0 {
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return nil
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}
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return nr.contextStack[stackLen-1]
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}
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// pushContext is called when we enter a statement.
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func (nr *nameResolver) pushContext() {
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nr.contextStack = append(nr.contextStack, &resolverContext{
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tableMap: map[string]int{},
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})
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}
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// popContext is called when we leave a statement.
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func (nr *nameResolver) popContext() {
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nr.contextStack = nr.contextStack[:len(nr.contextStack)-1]
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}
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// pushJoin is called when we enter a join node.
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func (nr *nameResolver) pushJoin(j *ast.Join) {
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ctx := nr.currentContext()
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ctx.joinNodeStack = append(ctx.joinNodeStack, j)
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}
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// popJoin is called when we leave a join node.
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func (nr *nameResolver) popJoin() {
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ctx := nr.currentContext()
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ctx.joinNodeStack = ctx.joinNodeStack[:len(ctx.joinNodeStack)-1]
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}
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// Enter implements ast.Visitor interface.
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func (nr *nameResolver) Enter(inNode ast.Node) (outNode ast.Node, skipChildren bool) {
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switch v := inNode.(type) {
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case *ast.SelectStmt:
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nr.pushContext()
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case *ast.TableRefsClause:
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nr.currentContext().inTableRefs = true
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case *ast.Join:
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nr.pushJoin(v)
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case *ast.OnCondition:
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nr.currentContext().inOnCondition = true
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case *ast.FieldList:
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nr.currentContext().inFieldList = true
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case *ast.GroupByClause:
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nr.currentContext().inGroupBy = true
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case *ast.HavingClause:
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nr.currentContext().inHaving = true
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case *ast.OrderByClause:
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nr.currentContext().inOrderBy = true
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case *ast.ByItem:
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if _, ok := v.Expr.(*ast.ColumnNameExpr); !ok {
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// If ByItem is not a single column name expression,
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// the resolving rule is different for order by clause.
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nr.currentContext().inByItemExpression = true
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}
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case *ast.InsertStmt:
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nr.pushContext()
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case *ast.DeleteStmt:
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nr.pushContext()
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case *ast.UpdateStmt:
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nr.pushContext()
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}
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return inNode, false
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}
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// Leave implements ast.Visitor interface.
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func (nr *nameResolver) Leave(inNode ast.Node) (node ast.Node, ok bool) {
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switch v := inNode.(type) {
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case *ast.TableName:
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nr.handleTableName(v)
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case *ast.ColumnNameExpr:
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nr.handleColumnName(v)
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case *ast.TableSource:
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nr.handleTableSource(v)
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case *ast.OnCondition:
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nr.currentContext().inOnCondition = false
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case *ast.Join:
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nr.handleJoin(v)
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nr.popJoin()
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case *ast.TableRefsClause:
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nr.currentContext().inTableRefs = false
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case *ast.FieldList:
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nr.handleFieldList(v)
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nr.currentContext().inFieldList = false
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case *ast.GroupByClause:
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nr.currentContext().inGroupBy = false
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case *ast.HavingClause:
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nr.currentContext().inHaving = false
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case *ast.OrderByClause:
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nr.currentContext().inOrderBy = false
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case *ast.ByItem:
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nr.currentContext().inByItemExpression = false
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case *ast.PositionExpr:
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nr.handlePosition(v)
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case *ast.SelectStmt:
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v.SetResultFields(nr.currentContext().fieldList)
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nr.popContext()
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case *ast.InsertStmt:
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nr.popContext()
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case *ast.DeleteStmt:
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nr.popContext()
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case *ast.UpdateStmt:
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nr.popContext()
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}
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return inNode, nr.Err == nil
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}
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// handleTableName looks up and set the schema information for table name
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// and set result fields for table name.
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func (nr *nameResolver) handleTableName(tn *ast.TableName) {
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if tn.Schema.L == "" {
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tn.Schema = nr.DefaultSchema
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}
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table, err := nr.Info.TableByName(tn.Schema, tn.Name)
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if err != nil {
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nr.Err = err
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return
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}
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tn.TableInfo = table.Meta()
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dbInfo, _ := nr.Info.SchemaByName(tn.Schema)
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tn.DBInfo = dbInfo
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rfs := make([]*ast.ResultField, len(tn.TableInfo.Columns))
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for i, v := range tn.TableInfo.Columns {
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expr := &ast.ValueExpr{}
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expr.SetType(&v.FieldType)
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rfs[i] = &ast.ResultField{
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Column: v,
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Table: tn.TableInfo,
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DBName: tn.Schema,
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Expr: expr,
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}
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}
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tn.SetResultFields(rfs)
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return
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}
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// handleTableSources checks name duplication
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// and puts the table source in current resolverContext.
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func (nr *nameResolver) handleTableSource(ts *ast.TableSource) {
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for _, v := range ts.GetResultFields() {
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v.TableAsName = ts.AsName
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}
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var name string
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if ts.AsName.L != "" {
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name = ts.AsName.L
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} else {
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tableName := ts.Source.(*ast.TableName)
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name = nr.tableUniqueName(tableName.Schema, tableName.Name)
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}
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ctx := nr.currentContext()
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if _, ok := ctx.tableMap[name]; ok {
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nr.Err = errors.Errorf("duplicated table/alias name %s", name)
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return
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}
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ctx.tableMap[name] = len(ctx.tables)
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ctx.tables = append(ctx.tables, ts)
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return
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}
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// handleJoin sets result fields for join.
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func (nr *nameResolver) handleJoin(j *ast.Join) {
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if j.Right == nil {
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j.SetResultFields(j.Left.GetResultFields())
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return
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}
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leftLen := len(j.Left.GetResultFields())
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rightLen := len(j.Right.GetResultFields())
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rfs := make([]*ast.ResultField, leftLen+rightLen)
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copy(rfs, j.Left.GetResultFields())
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copy(rfs[leftLen:], j.Right.GetResultFields())
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j.SetResultFields(rfs)
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}
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// handleColumnName looks up and sets ResultField for
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// the column name.
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func (nr *nameResolver) handleColumnName(cn *ast.ColumnNameExpr) {
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ctx := nr.currentContext()
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if ctx.inOnCondition {
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// In on condition, only tables within current join is available.
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nr.resolveColumnNameInOnCondition(cn)
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return
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}
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// Try to resolve the column name form top to bottom in the context stack.
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for i := len(nr.contextStack) - 1; i >= 0; i-- {
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if nr.resolveColumnNameInContext(nr.contextStack[i], cn) {
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// Column is already resolved or encountered an error.
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return
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}
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}
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nr.Err = errors.Errorf("unknown column %s", cn.Name.Name.L)
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}
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// resolveColumnNameInContext looks up and sets ResultField for a column with the ctx.
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func (nr *nameResolver) resolveColumnNameInContext(ctx *resolverContext, cn *ast.ColumnNameExpr) (done bool) {
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if ctx.inTableRefs {
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// In TableRefsClause, column reference only in join on condition which is handled before.
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return false
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}
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if ctx.inFieldList {
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// only resolve column using tables.
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return nr.resolveColumnInTableSources(cn, ctx.tables)
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}
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if ctx.inGroupBy {
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// From tables first, then field list.
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if ctx.inByItemExpression {
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// From table first, then field list.
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if nr.resolveColumnInTableSources(cn, ctx.tables) {
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return true
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}
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return nr.resolveColumnInResultFields(cn, ctx.fieldList)
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}
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// Field list first, then from table.
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if nr.resolveColumnInResultFields(cn, ctx.fieldList) {
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if nr.Err != nil {
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return true
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}
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// The column is resolved in field list, but we need to
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// try to overwrite the ResultField in table sources.
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nr.resolveColumnInTableSources(cn, ctx.tables)
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if nr.Err != nil {
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nr.Err = nil
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}
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return true
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}
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return false
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}
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if ctx.inHaving {
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// First group by, then field list.
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if nr.resolveColumnInResultFields(cn, ctx.groupBy) {
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return true
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}
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return nr.resolveColumnInResultFields(cn, ctx.fieldList)
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}
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if ctx.inOrderBy {
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if nr.resolveColumnInResultFields(cn, ctx.groupBy) {
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return true
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}
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if ctx.inByItemExpression {
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// From table first, then field list.
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if nr.resolveColumnInTableSources(cn, ctx.tables) {
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return true
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}
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return nr.resolveColumnInResultFields(cn, ctx.fieldList)
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}
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// Field list first, then from table.
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if nr.resolveColumnInResultFields(cn, ctx.fieldList) {
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return true
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}
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return nr.resolveColumnInTableSources(cn, ctx.tables)
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}
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// In where clause.
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return nr.resolveColumnInTableSources(cn, ctx.tables)
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}
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// resolveColumnNameInOnCondition resolves the column name in current join.
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func (nr *nameResolver) resolveColumnNameInOnCondition(cn *ast.ColumnNameExpr) {
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ctx := nr.currentContext()
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join := ctx.joinNodeStack[len(ctx.joinNodeStack)-1]
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tableSources := appendTableSources(nil, join)
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if !nr.resolveColumnInTableSources(cn, tableSources) {
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nr.Err = errors.Errorf("unkown column name %s", cn.Name.Name.O)
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}
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}
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func (nr *nameResolver) resolveColumnInTableSources(cn *ast.ColumnNameExpr, tableSources []*ast.TableSource) (done bool) {
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var matchedResultField *ast.ResultField
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tableNameL := cn.Name.Table.L
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columnNameL := cn.Name.Name.L
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if tableNameL != "" {
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var matchedTable ast.ResultSetNode
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for _, ts := range tableSources {
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if tableNameL == ts.AsName.L {
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// different table name.
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matchedTable = ts
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break
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}
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if tn, ok := ts.Source.(*ast.TableName); ok {
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if tableNameL == tn.Name.L {
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matchedTable = ts
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}
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}
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}
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if matchedTable != nil {
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resultFields := matchedTable.GetResultFields()
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for _, rf := range resultFields {
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if rf.ColumnAsName.L == columnNameL || rf.Column.Name.L == columnNameL {
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// resolve column.
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matchedResultField = rf
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break
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}
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}
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}
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} else {
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for _, ts := range tableSources {
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rfs := ts.GetResultFields()
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for _, rf := range rfs {
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matchAsName := rf.ColumnAsName.L != "" && rf.ColumnAsName.L == columnNameL
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matchColumnName := rf.ColumnAsName.L == "" && rf.Column.Name.L == columnNameL
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if matchAsName || matchColumnName {
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if matchedResultField != nil {
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nr.Err = errors.Errorf("column %s is ambiguous.", cn.Name.Name.O)
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return true
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}
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matchedResultField = rf
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}
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}
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}
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}
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if matchedResultField != nil {
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// Bind column.
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cn.Refer = matchedResultField
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return true
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}
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return false
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}
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func (nr *nameResolver) resolveColumnInResultFields(cn *ast.ColumnNameExpr, rfs []*ast.ResultField) bool {
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if cn.Name.Table.L != "" {
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// Skip result fields, resolve the column in table source.
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return false
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}
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var matched *ast.ResultField
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for _, rf := range rfs {
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matchAsName := cn.Name.Name.L == rf.ColumnAsName.L
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matchColumnName := rf.ColumnAsName.L == "" && cn.Name.Name.L == rf.Column.Name.L
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if matchAsName || matchColumnName {
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if rf.Column.Name.L == "" {
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// This is not a real table column, resolve it directly.
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cn.Refer = rf
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return true
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}
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if matched == nil {
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matched = rf
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} else {
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sameColumn := matched.Table.Name.L == rf.Table.Name.L && matched.Column.Name.L == rf.Column.Name.L
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if !sameColumn {
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nr.Err = errors.Errorf("column %s is ambiguous.", cn.Name.Name.O)
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return true
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}
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}
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}
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}
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if matched != nil {
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// Bind column.
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cn.Refer = matched
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return true
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}
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return false
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}
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// handleFieldList expands wild card field and set fieldList in current context.
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func (nr *nameResolver) handleFieldList(fieldList *ast.FieldList) {
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var resultFields []*ast.ResultField
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for _, v := range fieldList.Fields {
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resultFields = append(resultFields, nr.createResultFields(v)...)
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}
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nr.currentContext().fieldList = resultFields
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}
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func getInnerFromParentheses(expr ast.ExprNode) ast.ExprNode {
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if pexpr, ok := expr.(*ast.ParenthesesExpr); ok {
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return getInnerFromParentheses(pexpr.Expr)
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}
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return expr
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}
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// createResultFields creates result field list for a single select field.
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func (nr *nameResolver) createResultFields(field *ast.SelectField) (rfs []*ast.ResultField) {
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ctx := nr.currentContext()
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if field.WildCard != nil {
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if len(ctx.tables) == 0 {
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nr.Err = errors.Errorf("No table used.")
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return
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}
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if field.WildCard.Table.L == "" {
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for _, v := range ctx.tables {
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rfs = append(rfs, v.GetResultFields()...)
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}
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} else {
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name := nr.tableUniqueName(field.WildCard.Schema, field.WildCard.Table)
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tableIdx, ok := ctx.tableMap[name]
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if !ok {
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nr.Err = errors.Errorf("unknown table %s.", field.WildCard.Table.O)
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}
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rfs = ctx.tables[tableIdx].GetResultFields()
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}
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return
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}
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// The column is visited before so it must has been resolved already.
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rf := &ast.ResultField{ColumnAsName: field.AsName}
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innerExpr := getInnerFromParentheses(field.Expr)
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switch v := innerExpr.(type) {
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case *ast.ColumnNameExpr:
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rf.Column = v.Refer.Column
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rf.Table = v.Refer.Table
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rf.DBName = v.Refer.DBName
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rf.Expr = v.Refer.Expr
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default:
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rf.Column = &model.ColumnInfo{} // Empty column info.
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rf.Table = &model.TableInfo{} // Empty table info.
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rf.Expr = v
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}
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if field.AsName.L == "" {
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switch x := innerExpr.(type) {
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case *ast.ColumnNameExpr:
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var fieldText string
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if innerExpr.Text() != "" {
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fieldText = innerExpr.Text()
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} else {
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fieldText = field.Text()
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}
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fieldText = fieldText[len(fieldText)-len(x.Name.Name.L):]
|
|
rf.ColumnAsName = model.NewCIStr(fieldText)
|
|
case *ast.ValueExpr:
|
|
if innerExpr.Text() != "" {
|
|
rf.ColumnAsName = model.NewCIStr(innerExpr.Text())
|
|
} else {
|
|
rf.ColumnAsName = model.NewCIStr(field.Text())
|
|
}
|
|
default:
|
|
rf.ColumnAsName = model.NewCIStr(field.Text())
|
|
}
|
|
}
|
|
rfs = append(rfs, rf)
|
|
return
|
|
}
|
|
|
|
func appendTableSources(in []*ast.TableSource, resultSetNode ast.ResultSetNode) (out []*ast.TableSource) {
|
|
switch v := resultSetNode.(type) {
|
|
case *ast.TableSource:
|
|
out = append(in, v)
|
|
case *ast.Join:
|
|
out = appendTableSources(in, v.Left)
|
|
if v.Right != nil {
|
|
out = appendTableSources(out, v.Right)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
func (nr *nameResolver) tableUniqueName(schema, table model.CIStr) string {
|
|
if schema.L != "" && schema.L != nr.DefaultSchema.L {
|
|
return schema.L + "." + table.L
|
|
}
|
|
return table.L
|
|
}
|
|
|
|
func (nr *nameResolver) handlePosition(pos *ast.PositionExpr) {
|
|
ctx := nr.currentContext()
|
|
if pos.N < 1 || pos.N > len(ctx.fieldList) {
|
|
nr.Err = errors.Errorf("Unknown column '%d'", pos.N)
|
|
return
|
|
}
|
|
pos.Refer = ctx.fieldList[pos.N-1]
|
|
}
|