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*: replace cost model factor constants with system variable
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@eurekaka
eurekaka committed Sep 18, 2019
1 parent b25b703 commit f16e32b
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Showing 10 changed files with 268 additions and 98 deletions.
6 changes: 4 additions & 2 deletions planner/core/exhaust_physical_plans.go
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Original file line number Diff line number Diff line change
Expand Up @@ -651,10 +651,11 @@ func (p *LogicalJoin) constructInnerTableScanTask(
ds.stats.Cardinality[i] = 1
}
rowSize := ds.TblColHists.GetAvgRowSize(ds.TblCols, false)
sessVars := ds.ctx.GetSessionVars()
copTask := &copTask{
tablePlan: ts,
indexPlanFinished: true,
cst: ScanFactor * rowSize * ts.stats.RowCount,
cst: sessVars.ScanFactor * rowSize * ts.stats.RowCount,
tblColHists: ds.TblColHists,
keepOrder: ts.KeepOrder,
}
Expand Down Expand Up @@ -719,7 +720,8 @@ func (p *LogicalJoin) constructInnerIndexScanTask(
}
is.initSchema(ds.id, path.index, path.fullIdxCols, cop.tablePlan != nil)
rowSize := is.indexScanRowSize(path.index, ds)
cop.cst = rowCount * rowSize * ScanFactor
sessVars := ds.ctx.GetSessionVars()
cop.cst = rowCount * rowSize * sessVars.ScanFactor
indexConds, tblConds := splitIndexFilterConditions(filterConds, path.fullIdxCols, path.fullIdxColLens, ds.tableInfo)
tmpPath := &accessPath{
indexFilters: indexConds,
Expand Down
50 changes: 22 additions & 28 deletions planner/core/find_best_task.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,19 +34,6 @@ import (
)

const (
// NetworkFactor is the network cost of transferring 1 byte data.
NetworkFactor = 1.0
// CPUFactor is the CPU cost of processing one expression for one row.
CPUFactor = 3 * NetworkFactor
// CopCPUFactor is the CPU cost of processing one expression for one row in coprocessor.
CopCPUFactor = 3 * NetworkFactor
// ScanFactor is the IO cost of scanning 1 byte data on TiKV.
ScanFactor = 1.5 * NetworkFactor
// DescScanFactor is the IO cost of scanning 1 byte data on TiKV in desc order.
DescScanFactor = 2 * ScanFactor
memoryFactor = 0.001
concurrencyFactor = 3.0

selectionFactor = 0.8
distinctFactor = 0.8
)
Expand Down Expand Up @@ -516,9 +503,10 @@ func (ds *DataSource) convertToPartialIndexScan(prop *property.PhysicalProperty,
rowSize := is.indexScanRowSize(idx, ds)
isCovered = isCoveringIndex(ds.schema.Columns, path.fullIdxCols, path.fullIdxColLens, ds.tableInfo.PKIsHandle)
indexConds := path.indexFilters
sessVars := ds.ctx.GetSessionVars()
if indexConds != nil {
var selectivity float64
partialCost += rowCount * CopCPUFactor
partialCost += rowCount * sessVars.CopCPUFactor
if path.countAfterAccess > 0 {
selectivity = path.countAfterIndex / path.countAfterAccess
}
Expand All @@ -530,10 +518,10 @@ func (ds *DataSource) convertToPartialIndexScan(prop *property.PhysicalProperty,
}
indexPlan := PhysicalSelection{Conditions: indexConds}.Init(is.ctx, stats, ds.blockOffset)
indexPlan.SetChildren(is)
partialCost += rowCount * rowSize * NetworkFactor
partialCost += rowCount * rowSize * sessVars.NetworkFactor
return indexPlan, partialCost, rowCount, isCovered
}
partialCost += rowCount * rowSize * NetworkFactor
partialCost += rowCount * rowSize * sessVars.NetworkFactor
indexPlan = is
return indexPlan, partialCost, rowCount, isCovered
}
Expand All @@ -545,6 +533,7 @@ func (ds *DataSource) convertToPartialTableScan(prop *property.PhysicalProperty,
isCovered bool) {
ts, partialCost, rowCount := ds.getOriginalPhysicalTableScan(prop, path, false)
rowSize := ds.TblColHists.GetAvgRowSize(ds.TblCols, false)
sessVars := ds.ctx.GetSessionVars()
if len(ts.filterCondition) > 0 {
selectivity, _, err := ds.tableStats.HistColl.Selectivity(ds.ctx, ts.filterCondition)
if err != nil {
Expand All @@ -553,17 +542,18 @@ func (ds *DataSource) convertToPartialTableScan(prop *property.PhysicalProperty,
}
tablePlan = PhysicalSelection{Conditions: ts.filterCondition}.Init(ts.ctx, ts.stats.ScaleByExpectCnt(selectivity*rowCount), ds.blockOffset)
tablePlan.SetChildren(ts)
partialCost += rowCount * CopCPUFactor
partialCost += selectivity * rowCount * rowSize * NetworkFactor
partialCost += rowCount * sessVars.CopCPUFactor
partialCost += selectivity * rowCount * rowSize * sessVars.NetworkFactor
return tablePlan, partialCost, rowCount, true
}
partialCost += rowCount * rowSize * NetworkFactor
partialCost += rowCount * rowSize * sessVars.NetworkFactor
tablePlan = ts
return tablePlan, partialCost, rowCount, true
}

func (ds *DataSource) buildIndexMergeTableScan(prop *property.PhysicalProperty, tableFilters []expression.Expression, totalRowCount float64) (PhysicalPlan, float64) {
var partialCost float64
sessVars := ds.ctx.GetSessionVars()
ts := PhysicalTableScan{
Table: ds.tableInfo,
Columns: ds.Columns,
Expand All @@ -581,13 +571,13 @@ func (ds *DataSource) buildIndexMergeTableScan(prop *property.PhysicalProperty,
}
}
rowSize := ds.TblColHists.GetAvgRowSize(ds.TblCols, false)
partialCost += totalRowCount * rowSize * ScanFactor
partialCost += totalRowCount * rowSize * sessVars.ScanFactor
ts.stats = ds.tableStats.ScaleByExpectCnt(totalRowCount)
if ds.statisticTable.Pseudo {
ts.stats.StatsVersion = statistics.PseudoVersion
}
if len(tableFilters) > 0 {
partialCost += totalRowCount * CopCPUFactor
partialCost += totalRowCount * sessVars.CopCPUFactor
selectivity, _, err := ds.tableStats.HistColl.Selectivity(ds.ctx, tableFilters)
if err != nil {
logutil.BgLogger().Debug("calculate selectivity failed, use selection factor", zap.Error(err))
Expand Down Expand Up @@ -743,8 +733,9 @@ func (is *PhysicalIndexScan) initSchema(id int, idx *model.IndexInfo, idxExprCol
func (is *PhysicalIndexScan) addPushedDownSelection(copTask *copTask, p *DataSource, path *accessPath, finalStats *property.StatsInfo) {
// Add filter condition to table plan now.
indexConds, tableConds := path.indexFilters, path.tableFilters
sessVars := is.ctx.GetSessionVars()
if indexConds != nil {
copTask.cst += copTask.count() * CopCPUFactor
copTask.cst += copTask.count() * sessVars.CopCPUFactor
var selectivity float64
if path.countAfterAccess > 0 {
selectivity = path.countAfterIndex / path.countAfterAccess
Expand All @@ -757,7 +748,7 @@ func (is *PhysicalIndexScan) addPushedDownSelection(copTask *copTask, p *DataSou
}
if tableConds != nil {
copTask.finishIndexPlan()
copTask.cst += copTask.count() * CopCPUFactor
copTask.cst += copTask.count() * sessVars.CopCPUFactor
tableSel := PhysicalSelection{Conditions: tableConds}.Init(is.ctx, finalStats, is.blockOffset)
tableSel.SetChildren(copTask.tablePlan)
copTask.tablePlan = tableSel
Expand Down Expand Up @@ -995,8 +986,9 @@ func (ds *DataSource) convertToTableScan(prop *property.PhysicalProperty, candid

func (ts *PhysicalTableScan) addPushedDownSelection(copTask *copTask, stats *property.StatsInfo) {
// Add filter condition to table plan now.
sessVars := ts.ctx.GetSessionVars()
if len(ts.filterCondition) > 0 {
copTask.cst += copTask.count() * CopCPUFactor
copTask.cst += copTask.count() * sessVars.CopCPUFactor
sel := PhysicalSelection{Conditions: ts.filterCondition}.Init(ts.ctx, stats, ts.blockOffset)
sel.SetChildren(ts)
copTask.tablePlan = sel
Expand Down Expand Up @@ -1048,11 +1040,12 @@ func (ds *DataSource) getOriginalPhysicalTableScan(prop *property.PhysicalProper
// for all columns now, as we do in `deriveStatsByFilter`.
ts.stats = ds.tableStats.ScaleByExpectCnt(rowCount)
rowSize := ds.TblColHists.GetAvgRowSize(ds.TblCols, false)
cost := rowCount * rowSize * ScanFactor
sessVars := ds.ctx.GetSessionVars()
cost := rowCount * rowSize * sessVars.ScanFactor
if isMatchProp {
if prop.Items[0].Desc {
ts.Desc = true
cost = rowCount * rowSize * DescScanFactor
cost = rowCount * rowSize * sessVars.DescScanFactor
}
ts.KeepOrder = true
}
Expand Down Expand Up @@ -1090,11 +1083,12 @@ func (ds *DataSource) getOriginalPhysicalIndexScan(prop *property.PhysicalProper
}
is.stats = ds.tableStats.ScaleByExpectCnt(rowCount)
rowSize := is.indexScanRowSize(idx, ds)
cost := rowCount * rowSize * ScanFactor
sessVars := ds.ctx.GetSessionVars()
cost := rowCount * rowSize * sessVars.ScanFactor
if isMatchProp {
if prop.Items[0].Desc {
is.Desc = true
cost = rowCount * rowSize * DescScanFactor
cost = rowCount * rowSize * sessVars.DescScanFactor
}
is.KeepOrder = true
}
Expand Down
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