tidb flat_plan 代码
文件路径：/planner/core/flat_plan.go
/ Copyright 2022 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,
/ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/ See the License for the specific language governing permissions and
/ limitations under the License.
package core
import (
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/util/texttree"
)
/ FlatPhysicalPlan provides an easier structure to traverse a plan and collect needed information.
/ Note: Although it's named FlatPhysicalPlan, there also could be Insert, Delete and Update at the beginning of Main.
type FlatPhysicalPlan struct {
Main FlatPlanTree
CTEs []FlatPlanTree
/ InExecute and InExplain are expected to handle some special cases. Usually you don't need to use them.
/ InExecute means if the original plan tree contains Execute operator.
/
/ Be careful when trying to use this, InExecute is true doesn't mean we are handling an EXECUTE statement.
/ When collecting information from the plan in an EXECUTE statement, usually we directly use the plan
/ in Execute.Plan, not Execute itself, so InExecute will be false.
/
/ When will InExecute be true? When you're using "EXPLAIN FOR CONNECTION" to get the last plan of
/ a connection (usually we will record Explain.TargetPlan for an EXPLAIN statement) and that plan
/ is from an EXECUTE statement, we will collect from Execute itself, not directly from Execute.Plan,
/ then InExecute will be true.
InExecute bool
/ InExplain means if the original plan tree contains Explain operator.
InExplain bool
/ The fields below are only used when building the FlatPhysicalPlan.
buildSideFirst bool
ctesToFlatten []*PhysicalCTE
}
/ FlatPlanTree is a simplified plan tree.
/ It arranges all operators in the tree as a slice, ordered by the order of traversing the tree, which means a
/ depth-first traversal plus some special rule for some operators.
type FlatPlanTree []*FlatOperator
/ GetSelectPlan skips Insert, Delete and Update at the beginning of the FlatPlanTree.
/ Note:
/
/ It returns a reference to the original FlatPlanTree, please avoid modifying the returned value.
/ Since you get a part of the original slice, you need to adjust the FlatOperator.Depth and FlatOperator.ChildrenIdx when using them.
func (e FlatPlanTree) GetSelectPlan() FlatPlanTree {
if len(e) == 0 {
return nil
}
for i, op := range e {
switch op.Origin.(type) {
case *Insert, *Delete, *Update:
default:
return e[i:]
}
}
return nil
}
/ FlatOperator is a simplified operator.
/ It contains a reference to the original operator and some usually needed information.
type FlatOperator struct {
/ A reference to the original operator.
Origin Plan
/ With ChildrenIdx and ChildrenEndIdx, we can locate every children subtrees of this operator in the FlatPlanTree.
/ For example, the first children subtree is flatTree[ChildrenIdx[0] : ChildrenIdx[1]], the last children subtree
/ is flatTree[ChildrenIdx[n-1] : ChildrenEndIdx].
/ ChildrenIdx is the indexes of the children of this operator in the FlatPlanTree.
/ It's ordered from small to large.
ChildrenIdx []int
/ ChildrenEndIdx is the index of the last operator of children subtrees of this operator in the FlatPlanTree.
ChildrenEndIdx int
/ NeedReverseDriverSide means if we need to reverse the order of children to keep build side before probe side.
/
/ Specifically, it means if the below are all true:
/ 1. this operator has two children
/ 2. the first child's Label is the probe side and the second's is the build side.
/
/ If you call FlattenPhysicalPlan with buildSideFirst true, NeedReverseDriverSide will be useless.
NeedReverseDriverSide bool
Depth uint32
Label OperatorLabel
IsRoot bool
StoreType kv.StoreType
/ ReqType is only meaningful when IsRoot is false.
ReqType ReadReqType
/ The below two fields are mainly for text tree formatting. See texttree.PrettyIdentifier().
TextTreeIndent string
IsLastChild bool
IsPhysicalPlan bool
}
/ OperatorLabel acts as some additional information to the name, usually it means its relationship with its parent.
/ It's useful for index join, apply, index lookup, cte and so on.
type OperatorLabel uint8
const (
/ Empty means OperatorLabel is meaningless for this operator.
Empty OperatorLabel = iota
/ BuildSide means this operator is at the build side of its parent
BuildSide
/ ProbeSide means this operator is at the probe side of its parent
ProbeSide
/ SeedPart means this operator is the seed part of its parent (a cte)
SeedPart
/ RecursivePart means this operator is the recursive part of its parent (a cte)
RecursivePart
)
func (d OperatorLabel) String() string {
switch d {
case Empty:
return ""
case BuildSide:
return "(Build)"
case ProbeSide:
return "(Probe)"
case SeedPart:
return "(Seed Part)"
case RecursivePart:
return "(Recursive Part)"
}
return ""
}
type operatorCtx struct {
depth uint32
label OperatorLabel
isRoot bool
storeType kv.StoreType
reqType ReadReqType
indent string
isLastChild bool
}
/ FlattenPhysicalPlan generates a FlatPhysicalPlan from a PhysicalPlan, Insert, Delete, Update, Explain or Execute.
func FlattenPhysicalPlan(p Plan, buildSideFirst bool) *FlatPhysicalPlan {
if p == nil {
return nil
}
res := &FlatPhysicalPlan{
buildSideFirst: buildSideFirst,
}
initInfo := &operatorCtx{
depth: 0,
label: Empty,
isRoot: true,
storeType: kv.TiDB,
indent: "",
isLastChild: true,
}
res.Main, _ = res.flattenRecursively(p, initInfo, nil)
flattenedCTEPlan := make(map[int]struct{}, len(res.ctesToFlatten))
/ Note that ctesToFlatten may be modified during the loop, so we manually loop over it instead of using for...range.
for i := 0; i < len(res.ctesToFlatten); i++ {
cte := res.ctesToFlatten[i]
cteDef := (*CTEDefinition)(cte)
if _, ok := flattenedCTEPlan[cteDef.CTE.IDForStorage]; ok {
continue
}
cteExplained := res.flattenCTERecursively(cteDef, initInfo, nil)
res.CTEs = append(res.CTEs, cteExplained)
flattenedCTEPlan[cteDef.CTE.IDForStorage] = struct{}{}
}
return res
}
func (f *FlatPhysicalPlan) flattenSingle(p Plan, info *operatorCtx) *FlatOperator {
/ Some operators are not initialized and given an ExplainID. So their explain IDs are "_0"
/ (when in EXPLAIN FORMAT = 'brief' it will be ""), we skip such operators.
/ Examples: Explain, Execute
if len(p.TP()) == 0 && p.ID() == 0 {
return nil
}
res := &FlatOperator{
Origin: p,
Label: info.label,
IsRoot: info.isRoot,
StoreType: info.storeType,
Depth: info.depth,
ReqType: info.reqType,
TextTreeIndent: info.indent,
IsLastChild: info.isLastChild,
}
if _, ok := p.(PhysicalPlan); ok {
res.IsPhysicalPlan = true
}
return res
}
/ Note that info should not be modified in this method.
func (f *FlatPhysicalPlan) flattenRecursively(p Plan, info *operatorCtx, target FlatPlanTree) (res FlatPlanTree, idx int) {
idx = -1
flat := f.flattenSingle(p, info)
if flat != nil {
target = append(target, flat)
idx = len(target) - 1
}
childIdxs := make([]int, 0)
var childIdx int
childCtx := &operatorCtx{
depth: info.depth + 1,
isRoot: info.isRoot,
storeType: info.storeType,
reqType: info.reqType,
indent: texttree.Indent4Child(info.indent, info.isLastChild),
}
/ For physical operators, we just enumerate their children and collect their information.
/ Note that some physical operators are special, and they are handled below this part.
if physPlan, ok := p.(PhysicalPlan); ok {
label := make([]OperatorLabel, len(physPlan.Children()))
switch plan := physPlan.(type) {
case *PhysicalApply:
label[plan.InnerChildIdx] = ProbeSide
label[1-plan.InnerChildIdx] = BuildSide
case *PhysicalHashJoin:
if plan.UseOuterToBuild {
label[plan.InnerChildIdx] = ProbeSide
label[1-plan.InnerChildIdx] = BuildSide
} else {
label[plan.InnerChildIdx] = BuildSide
label[1-plan.InnerChildIdx] = ProbeSide
}
case *PhysicalMergeJoin:
if plan.JoinType == RightOuterJoin {
label[0] = BuildSide
label[1] = ProbeSide
} else {
label[0] = ProbeSide
label[1] = BuildSide
}
case *PhysicalIndexJoin:
label[plan.InnerChildIdx] = ProbeSide
label[1-plan.InnerChildIdx] = BuildSide
case *PhysicalIndexMergeJoin:
label[plan.InnerChildIdx] = ProbeSide
label[1-plan.InnerChildIdx] = BuildSide
case *PhysicalIndexHashJoin:
label[plan.InnerChildIdx] = ProbeSide
label[1-plan.InnerChildIdx] = BuildSide
}
children := make([]PhysicalPlan, len(physPlan.Children()))
copy(children, physPlan.Children())
if len(label) == 2 &&
label[0] == ProbeSide &&
label[1] == BuildSide {
if f.buildSideFirst {
/ Put the build side before the probe side if buildSideFirst is true.
label[0], label[1] = label[1], label[0]
children[0], children[1] = children[1], children[0]
} else if flat != nil {
/ Set NeedReverseDriverSide to true if buildSideFirst is false.
flat.NeedReverseDriverSide = true
}
}
for i := range children {
childCtx.label = label[i]
childCtx.isLastChild = i == len(children)-1
target, childIdx = f.flattenRecursively(children[i], childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
}
/ For part of physical operators and some special operators, we need some special logic to get their "children".
/ For PhysicalCTE, we need to add the plan tree into flatTree.ctesToFlatten.
switch plan := p.(type) {
case *PhysicalTableReader:
childCtx.isRoot = false
childCtx.storeType = plan.StoreType
childCtx.reqType = plan.ReadReqType
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.tablePlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
case *PhysicalIndexReader:
childCtx.isRoot = false
childCtx.reqType = Cop
childCtx.storeType = kv.TiKV
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.indexPlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
case *PhysicalIndexLookUpReader:
childCtx.isRoot = false
childCtx.reqType = Cop
childCtx.storeType = kv.TiKV
childCtx.label = BuildSide
childCtx.isLastChild = false
target, childIdx = f.flattenRecursively(plan.indexPlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
childCtx.label = ProbeSide
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.tablePlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
case *PhysicalIndexMergeReader:
childCtx.isRoot = false
childCtx.reqType = Cop
childCtx.storeType = kv.TiKV
for _, pchild := range plan.partialPlans {
childCtx.label = BuildSide
childCtx.isLastChild = false
target, childIdx = f.flattenRecursively(pchild, childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
childCtx.label = ProbeSide
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.tablePlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
case *PhysicalShuffleReceiverStub:
childCtx.isRoot = true
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.DataSource, childCtx, target)
childIdxs = append(childIdxs, childIdx)
case *PhysicalCTE:
f.ctesToFlatten = append(f.ctesToFlatten, plan)
case *Insert:
if plan.SelectPlan != nil {
childCtx.isRoot = true
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.SelectPlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
case *Update:
if plan.SelectPlan != nil {
childCtx.isRoot = true
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.SelectPlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
case *Delete:
if plan.SelectPlan != nil {
childCtx.isRoot = true
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.SelectPlan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
case *Execute:
f.InExecute = true
if plan.Plan != nil {
childCtx.isRoot = true
childCtx.indent = info.indent
childCtx.label = Empty
childCtx.isLastChild = true
target, childIdx = f.flattenRecursively(plan.Plan, childCtx, target)
childIdxs = append(childIdxs, childIdx)
}
case *Explain:
f.InExplain = true
/ Explain is ignored in flattenSingle(). We start to explain its TargetPlan from a new operatorCtx.
if plan.TargetPlan != nil {
initInfo := &operatorCtx{
depth: 0,
label: Empty,
isRoot: true,
storeType: kv.TiDB,
indent: "",
isLastChild: true,
}
target, childIdx = f.flattenRecursively(plan.TargetPlan, initInfo, target)
childIdxs = append(childIdxs, childIdx)
}
}
if flat != nil {
flat.ChildrenIdx = childIdxs
flat.ChildrenEndIdx = len(target) - 1
}
return target, idx
}
func (f *FlatPhysicalPlan) flattenCTERecursively(cteDef *CTEDefinition, info *operatorCtx, target FlatPlanTree) FlatPlanTree {
flat := f.flattenSingle(cteDef, info)
if flat != nil {
target = append(target, flat)
}
childIdxs := make([]int, 0)
var childIdx int
childInfo := &operatorCtx{
depth: info.depth + 1,
label: SeedPart,
isRoot: true,
storeType: kv.TiDB,
indent: texttree.Indent4Child(info.indent, info.isLastChild),
isLastChild: cteDef.RecurPlan == nil,
}
target, childIdx = f.flattenRecursively(cteDef.SeedPlan, childInfo, target)
childIdxs = append(childIdxs, childIdx)
if cteDef.RecurPlan != nil {
childInfo.label = RecursivePart
childInfo.isLastChild = true
target, childIdx = f.flattenRecursively(cteDef.RecurPlan, childInfo, target)
childIdxs = append(childIdxs, childIdx)
}
if flat != nil {
flat.ChildrenIdx = childIdxs
}
return target
}
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