mirror of
https://github.com/go-gitea/gitea
synced 2024-11-16 07:04:25 +00:00
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
110 lines
2.7 KiB
Go
110 lines
2.7 KiB
Go
// Copyright 2015 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 plan
|
|
|
|
import (
|
|
"math"
|
|
)
|
|
|
|
// Pre-defined cost factors.
|
|
const (
|
|
FullRangeCount = 10000
|
|
HalfRangeCount = 4000
|
|
MiddleRangeCount = 100
|
|
RowCost = 1.0
|
|
IndexCost = 2.0
|
|
SortCost = 2.0
|
|
FilterRate = 0.5
|
|
)
|
|
|
|
// CostEstimator estimates the cost of a plan.
|
|
type costEstimator struct {
|
|
}
|
|
|
|
// Enter implements Visitor Enter interface.
|
|
func (c *costEstimator) Enter(p Plan) (Plan, bool) {
|
|
return p, false
|
|
}
|
|
|
|
// Leave implements Visitor Leave interface.
|
|
func (c *costEstimator) Leave(p Plan) (Plan, bool) {
|
|
switch v := p.(type) {
|
|
case *IndexScan:
|
|
c.indexScan(v)
|
|
case *Limit:
|
|
v.rowCount = v.Src().RowCount()
|
|
v.startupCost = v.Src().StartupCost()
|
|
v.totalCost = v.Src().TotalCost()
|
|
case *SelectFields:
|
|
if v.Src() != nil {
|
|
v.startupCost = v.Src().StartupCost()
|
|
v.rowCount = v.Src().RowCount()
|
|
v.totalCost = v.Src().TotalCost()
|
|
}
|
|
case *SelectLock:
|
|
v.startupCost = v.Src().StartupCost()
|
|
v.rowCount = v.Src().RowCount()
|
|
v.totalCost = v.Src().TotalCost()
|
|
case *Sort:
|
|
// Sort plan must retrieve all the rows before returns the first row.
|
|
v.startupCost = v.Src().TotalCost() + v.Src().RowCount()*SortCost
|
|
if v.limit == 0 {
|
|
v.rowCount = v.Src().RowCount()
|
|
} else {
|
|
v.rowCount = math.Min(v.Src().RowCount(), v.limit)
|
|
}
|
|
v.totalCost = v.startupCost + v.rowCount*RowCost
|
|
case *TableScan:
|
|
c.tableScan(v)
|
|
}
|
|
return p, true
|
|
}
|
|
|
|
func (c *costEstimator) tableScan(v *TableScan) {
|
|
var rowCount float64 = FullRangeCount
|
|
for _, con := range v.AccessConditions {
|
|
rowCount *= guesstimateFilterRate(con)
|
|
}
|
|
v.startupCost = 0
|
|
if v.limit == 0 {
|
|
// limit is zero means no limit.
|
|
v.rowCount = rowCount
|
|
} else {
|
|
v.rowCount = math.Min(rowCount, v.limit)
|
|
}
|
|
v.totalCost = v.rowCount * RowCost
|
|
}
|
|
|
|
func (c *costEstimator) indexScan(v *IndexScan) {
|
|
var rowCount float64 = FullRangeCount
|
|
for _, con := range v.AccessConditions {
|
|
rowCount *= guesstimateFilterRate(con)
|
|
}
|
|
v.startupCost = 0
|
|
if v.limit == 0 {
|
|
// limit is zero means no limit.
|
|
v.rowCount = rowCount
|
|
} else {
|
|
v.rowCount = math.Min(rowCount, v.limit)
|
|
}
|
|
v.totalCost = v.rowCount * RowCost
|
|
}
|
|
|
|
// EstimateCost estimates the cost of the plan.
|
|
func EstimateCost(p Plan) float64 {
|
|
var estimator costEstimator
|
|
p.Accept(&estimator)
|
|
return p.TotalCost()
|
|
}
|