130 lines
4.4 KiB
Go
130 lines
4.4 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 plan
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import (
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"github.com/juju/errors"
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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/context"
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"github.com/pingcap/tidb/infoschema"
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"github.com/pingcap/tidb/mysql"
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"github.com/pingcap/tidb/terror"
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)
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// AllowCartesianProduct means whether tidb allows cartesian join without equal conditions.
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var AllowCartesianProduct = true
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// Optimize does optimization and creates a Plan.
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// The node must be prepared first.
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func Optimize(ctx context.Context, node ast.Node, is infoschema.InfoSchema) (Plan, error) {
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// We have to infer type again because after parameter is set, the expression type may change.
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if err := InferType(node); err != nil {
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return nil, errors.Trace(err)
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}
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allocator := new(idAllocator)
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builder := &planBuilder{
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ctx: ctx,
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is: is,
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colMapper: make(map[*ast.ColumnNameExpr]int),
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allocator: allocator}
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p := builder.build(node)
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if builder.err != nil {
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return nil, errors.Trace(builder.err)
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}
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if logic, ok := p.(LogicalPlan); ok {
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var err error
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_, logic, err = logic.PredicatePushDown(nil)
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if err != nil {
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return nil, errors.Trace(err)
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}
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solver := &aggPushDownSolver{
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ctx: ctx,
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alloc: allocator,
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}
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solver.aggPushDown(logic)
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_, err = logic.PruneColumnsAndResolveIndices(p.GetSchema())
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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 !AllowCartesianProduct && existsCartesianProduct(logic) {
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return nil, ErrCartesianProductUnsupported
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}
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info, err := logic.convert2PhysicalPlan(&requiredProperty{})
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if err != nil {
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return nil, errors.Trace(err)
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}
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pp := info.p
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pp = EliminateProjection(pp)
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log.Debugf("[PLAN] %s", ToString(pp))
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return pp, nil
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}
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return p, nil
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}
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func existsCartesianProduct(p LogicalPlan) bool {
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if join, ok := p.(*Join); ok && len(join.EqualConditions) == 0 {
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return join.JoinType == InnerJoin || join.JoinType == LeftOuterJoin || join.JoinType == RightOuterJoin
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}
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for _, child := range p.GetChildren() {
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if existsCartesianProduct(child.(LogicalPlan)) {
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return true
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}
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}
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return false
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}
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// PrepareStmt prepares a raw statement parsed from parser.
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// The statement must be prepared before it can be passed to optimize function.
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// We pass InfoSchema instead of getting from Context in case it is changed after resolving name.
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func PrepareStmt(is infoschema.InfoSchema, ctx context.Context, node ast.Node) error {
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if err := Preprocess(node, is, ctx); err != nil {
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return errors.Trace(err)
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}
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if err := Validate(node, true); err != nil {
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return errors.Trace(err)
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}
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return nil
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}
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// Optimizer error codes.
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const (
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CodeOneColumn terror.ErrCode = 1
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CodeSameColumns terror.ErrCode = 2
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CodeInvalidWildCard terror.ErrCode = 3
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CodeUnsupported terror.ErrCode = 4
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CodeInvalidGroupFuncUse terror.ErrCode = 5
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CodeIllegalReference terror.ErrCode = 6
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)
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// Optimizer base errors.
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var (
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ErrOneColumn = terror.ClassOptimizer.New(CodeOneColumn, "Operand should contain 1 column(s)")
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ErrSameColumns = terror.ClassOptimizer.New(CodeSameColumns, "Operands should contain same columns")
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ErrInvalidWildCard = terror.ClassOptimizer.New(CodeInvalidWildCard, "Wildcard fields without any table name appears in wrong place")
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ErrCartesianProductUnsupported = terror.ClassOptimizer.New(CodeUnsupported, "Cartesian product is unsupported")
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ErrInvalidGroupFuncUse = terror.ClassOptimizer.New(CodeInvalidGroupFuncUse, "Invalid use of group function")
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ErrIllegalReference = terror.ClassOptimizer.New(CodeIllegalReference, "Illegal reference")
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)
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func init() {
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mySQLErrCodes := map[terror.ErrCode]uint16{
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CodeOneColumn: mysql.ErrOperandColumns,
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CodeSameColumns: mysql.ErrOperandColumns,
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CodeInvalidWildCard: mysql.ErrParse,
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CodeInvalidGroupFuncUse: mysql.ErrInvalidGroupFuncUse,
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CodeIllegalReference: mysql.ErrIllegalReference,
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}
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terror.ErrClassToMySQLCodes[terror.ClassOptimizer] = mySQLErrCodes
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}
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