102 lines
3.5 KiB
Go
102 lines
3.5 KiB
Go
// Copyright 2018 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 cascades
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import (
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plannercore "github.com/pingcap/tidb/planner/core"
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impl "github.com/pingcap/tidb/planner/implementation"
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"github.com/pingcap/tidb/planner/memo"
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"github.com/pingcap/tidb/planner/property"
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)
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// ImplementationRule defines the interface for implementation rules.
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type ImplementationRule interface {
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// Match checks if current GroupExpr matches this rule under required physical property.
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Match(expr *memo.GroupExpr, prop *property.PhysicalProperty) (matched bool)
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// OnImplement generates physical plan using this rule for current GroupExpr. Note that
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// childrenReqProps of generated physical plan should be set correspondingly in this function.
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OnImplement(expr *memo.GroupExpr, reqProp *property.PhysicalProperty) (memo.Implementation, error)
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}
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// GetImplementationRules gets the all the candidate implementation rules based
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// on the logical plan node.
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func GetImplementationRules(node plannercore.LogicalPlan) []ImplementationRule {
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operand := memo.GetOperand(node)
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return implementationMap[operand]
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}
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var implementationMap = map[memo.Operand][]ImplementationRule{
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/**
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OperandSelection: []ImplementationRule{
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nil,
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},
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OperandProjection: []ImplementationRule{
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nil,
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},
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*/
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memo.OperandTableDual: {
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&ImplTableDual{},
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},
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memo.OperandProjection: {
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&ImplProjection{},
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},
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}
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// ImplTableDual implements LogicalTableDual as PhysicalTableDual.
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type ImplTableDual struct {
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}
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// Match implements ImplementationRule Match interface.
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func (r *ImplTableDual) Match(expr *memo.GroupExpr, prop *property.PhysicalProperty) (matched bool) {
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if !prop.IsEmpty() {
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return false
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}
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return true
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}
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// OnImplement implements ImplementationRule OnImplement interface.
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func (r *ImplTableDual) OnImplement(expr *memo.GroupExpr, reqProp *property.PhysicalProperty) (memo.Implementation, error) {
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logicProp := expr.Group.Prop
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logicDual := expr.ExprNode.(*plannercore.LogicalTableDual)
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dual := plannercore.PhysicalTableDual{RowCount: logicDual.RowCount}.Init(logicDual.SCtx(), logicProp.Stats)
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dual.SetSchema(logicProp.Schema)
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return impl.NewTableDualImpl(dual), nil
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}
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// ImplProjection implements LogicalProjection as PhysicalProjection.
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type ImplProjection struct {
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}
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// Match implements ImplementationRule Match interface.
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func (r *ImplProjection) Match(expr *memo.GroupExpr, prop *property.PhysicalProperty) (matched bool) {
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return true
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}
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// OnImplement implements ImplementationRule OnImplement interface.
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func (r *ImplProjection) OnImplement(expr *memo.GroupExpr, reqProp *property.PhysicalProperty) (memo.Implementation, error) {
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logicProp := expr.Group.Prop
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logicProj := expr.ExprNode.(*plannercore.LogicalProjection)
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childProp, ok := logicProj.TryToGetChildProp(reqProp)
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if !ok {
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return nil, nil
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}
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proj := plannercore.PhysicalProjection{
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Exprs: logicProj.Exprs,
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CalculateNoDelay: logicProj.CalculateNoDelay,
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AvoidColumnEvaluator: logicProj.AvoidColumnEvaluator,
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}.Init(logicProj.SCtx(), logicProp.Stats.ScaleByExpectCnt(reqProp.ExpectedCnt), childProp)
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proj.SetSchema(logicProp.Schema)
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return impl.NewProjectionImpl(proj), nil
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}
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