149b8184a6
Scheme info is generated when converting the initial logical plan tree to Group, so in exploration phase, we need to fill in the schema of newly built Group; stats info is generated in lazy style when it is needed during implementation phase.
127 lines
3.4 KiB
Go
127 lines
3.4 KiB
Go
// Copyright 2018 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,
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package memo
|
|
|
|
import (
|
|
"container/list"
|
|
"fmt"
|
|
|
|
"github.com/pingcap/tidb/planner/property"
|
|
)
|
|
|
|
// Group is short for expression Group, which is used to store all the
|
|
// logically equivalent expressions. It's a set of GroupExpr.
|
|
type Group struct {
|
|
Equivalents *list.List
|
|
|
|
FirstExpr map[Operand]*list.Element
|
|
Fingerprints map[string]*list.Element
|
|
|
|
Explored bool
|
|
SelfFingerprint string
|
|
|
|
ImplMap map[string]Implementation
|
|
Prop *property.LogicalProperty
|
|
}
|
|
|
|
// NewGroup creates a new Group.
|
|
func NewGroup(e *GroupExpr) *Group {
|
|
g := &Group{
|
|
Equivalents: list.New(),
|
|
Fingerprints: make(map[string]*list.Element),
|
|
FirstExpr: make(map[Operand]*list.Element),
|
|
ImplMap: make(map[string]Implementation),
|
|
}
|
|
g.Insert(e)
|
|
return g
|
|
}
|
|
|
|
// FingerPrint returns the unique fingerprint of the Group.
|
|
func (g *Group) FingerPrint() string {
|
|
if g.SelfFingerprint == "" {
|
|
g.SelfFingerprint = fmt.Sprintf("%p", g)
|
|
}
|
|
return g.SelfFingerprint
|
|
}
|
|
|
|
// Insert a nonexistent Group expression.
|
|
func (g *Group) Insert(e *GroupExpr) bool {
|
|
if g.Exists(e) {
|
|
return false
|
|
}
|
|
|
|
operand := GetOperand(e.ExprNode)
|
|
var newEquiv *list.Element
|
|
mark, hasMark := g.FirstExpr[operand]
|
|
if hasMark {
|
|
newEquiv = g.Equivalents.InsertAfter(e, mark)
|
|
} else {
|
|
newEquiv = g.Equivalents.PushBack(e)
|
|
g.FirstExpr[operand] = newEquiv
|
|
}
|
|
g.Fingerprints[e.FingerPrint()] = newEquiv
|
|
return true
|
|
}
|
|
|
|
// Delete an existing Group expression.
|
|
func (g *Group) Delete(e *GroupExpr) {
|
|
fingerprint := e.FingerPrint()
|
|
equiv, ok := g.Fingerprints[fingerprint]
|
|
if !ok {
|
|
return // Can not find the target GroupExpr.
|
|
}
|
|
|
|
g.Equivalents.Remove(equiv)
|
|
delete(g.Fingerprints, fingerprint)
|
|
|
|
operand := GetOperand(equiv.Value.(*GroupExpr).ExprNode)
|
|
if g.FirstExpr[operand] != equiv {
|
|
return // The target GroupExpr is not the first Element of the same Operand.
|
|
}
|
|
|
|
nextElem := equiv.Next()
|
|
if nextElem != nil && GetOperand(nextElem.Value.(*GroupExpr).ExprNode) == operand {
|
|
g.FirstExpr[operand] = nextElem
|
|
return // The first Element of the same Operand has been changed.
|
|
}
|
|
delete(g.FirstExpr, operand)
|
|
}
|
|
|
|
// Exists checks whether a Group expression existed in a Group.
|
|
func (g *Group) Exists(e *GroupExpr) bool {
|
|
_, ok := g.Fingerprints[e.FingerPrint()]
|
|
return ok
|
|
}
|
|
|
|
// GetFirstElem returns the first Group expression which matches the Operand.
|
|
// Return a nil pointer if there isn't.
|
|
func (g *Group) GetFirstElem(operand Operand) *list.Element {
|
|
if operand == OperandAny {
|
|
return g.Equivalents.Front()
|
|
}
|
|
return g.FirstExpr[operand]
|
|
}
|
|
|
|
// GetImpl returns the best Implementation satisfy the physical property.
|
|
func (g *Group) GetImpl(prop *property.PhysicalProperty) Implementation {
|
|
key := prop.HashCode()
|
|
return g.ImplMap[string(key)]
|
|
}
|
|
|
|
// InsertImpl inserts the best Implementation satisfy the physical property.
|
|
func (g *Group) InsertImpl(prop *property.PhysicalProperty, impl Implementation) {
|
|
key := prop.HashCode()
|
|
g.ImplMap[string(key)] = impl
|
|
}
|