b6a95a8cb3
* Dropped unused codekit config * Integrated dynamic and static bindata for public * Ignore public bindata * Add a general generate make task * Integrated flexible public assets into web command * Updated vendoring, added all missiong govendor deps * Made the linter happy with the bindata and dynamic code * Moved public bindata definition to modules directory * Ignoring the new bindata path now * Updated to the new public modules import path * Updated public bindata command and drop the new prefix
127 lines
3.4 KiB
Go
127 lines
3.4 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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"math"
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"github.com/pingcap/tidb/ast"
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)
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// Plan is a description of an execution flow.
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// It is created from ast.Node first, then optimized by optimizer,
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// then used by executor to create a Cursor which executes the statement.
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type Plan interface {
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// Accept a visitor, implementation should call Visitor.Enter first,
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// then call children Accept methods, finally call Visitor.Leave.
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Accept(v Visitor) (out Plan, ok bool)
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// Fields returns the result fields of the plan.
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Fields() []*ast.ResultField
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// SetFields sets the results fields of the plan.
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SetFields(fields []*ast.ResultField)
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// The cost before returning fhe first row.
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StartupCost() float64
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// The cost after returning all the rows.
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TotalCost() float64
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// The expected row count.
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RowCount() float64
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// SetLimit is used to push limit to upstream to estimate the cost.
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SetLimit(limit float64)
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}
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// WithSrcPlan is a Plan has a source Plan.
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type WithSrcPlan interface {
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Plan
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Src() Plan
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SetSrc(src Plan)
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}
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// Visitor visits a Plan.
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type Visitor interface {
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// Enter is called before visit children.
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// The out plan should be of exactly the same type as the in plan.
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// if skipChildren is true, the children should not be visited.
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Enter(in Plan) (out Plan, skipChildren bool)
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// Leave is called after children has been visited, the out Plan can
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// be another type, this is different than ast.Visitor Leave, because
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// Plans only contain children plans as Plan interface type, so it is safe
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// to return a different type of plan.
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Leave(in Plan) (out Plan, ok bool)
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}
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// basePlan implements base Plan interface.
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// Should be used as embedded struct in Plan implementations.
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type basePlan struct {
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fields []*ast.ResultField
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startupCost float64
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totalCost float64
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rowCount float64
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limit float64
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}
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// StartupCost implements Plan StartupCost interface.
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func (p *basePlan) StartupCost() float64 {
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return p.startupCost
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}
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// TotalCost implements Plan TotalCost interface.
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func (p *basePlan) TotalCost() float64 {
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return p.totalCost
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}
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// RowCount implements Plan RowCount interface.
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func (p *basePlan) RowCount() float64 {
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if p.limit == 0 {
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return p.rowCount
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}
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return math.Min(p.rowCount, p.limit)
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}
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// SetLimit implements Plan SetLimit interface.
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func (p *basePlan) SetLimit(limit float64) {
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p.limit = limit
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}
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// Fields implements Plan Fields interface.
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func (p *basePlan) Fields() []*ast.ResultField {
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return p.fields
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}
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// SetFields implements Plan SetFields interface.
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func (p *basePlan) SetFields(fields []*ast.ResultField) {
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p.fields = fields
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}
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// srcPlan implements base PlanWithSrc interface.
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type planWithSrc struct {
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basePlan
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src Plan
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}
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// Src implements PlanWithSrc interface.
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func (p *planWithSrc) Src() Plan {
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return p.src
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}
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// SetSrc implements PlanWithSrc interface.
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func (p *planWithSrc) SetSrc(src Plan) {
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p.src = src
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}
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// SetLimit implements Plan interface.
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func (p *planWithSrc) SetLimit(limit float64) {
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p.limit = limit
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p.src.SetLimit(limit)
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}
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