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stats: fix selectivity estimation for primary key (#8134) #8149

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merged 3 commits into from
Nov 2, 2018
Merged

stats: fix selectivity estimation for primary key (#8134) #8149

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15b0276
stats: fix selectivity estimation for primary key (#8134)
alivxxx Nov 1, 2018
fbb6b25
Merge branch 'release-2.1' into pk-stats
alivxxx Nov 2, 2018
78fda0c
Merge branch 'release-2.1' into pk-stats
XuHuaiyu Nov 2, 2018
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2 changes: 1 addition & 1 deletion statistics/bootstrap.go
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Original file line number Diff line number Diff line change
Expand Up @@ -120,7 +120,7 @@ func (h *Handle) initStatsHistograms4Chunk(is infoschema.InfoSchema, tables stat
continue
}
hist := NewHistogram(id, ndv, nullCount, version, &colInfo.FieldType, 0, totColSize)
table.Columns[hist.ID] = &Column{Histogram: *hist, Info: colInfo, Count: nullCount}
table.Columns[hist.ID] = &Column{Histogram: *hist, Info: colInfo, Count: nullCount, isHandle: tbl.Meta().PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag)}
}
}
}
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1 change: 1 addition & 0 deletions statistics/dump.go
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Expand Up @@ -216,6 +216,7 @@ func TableStatsFromJSON(tableInfo *model.TableInfo, physicalID int64, jsonTbl *J
CMSketch: CMSketchFromProto(jsonCol.CMSketch),
Info: colInfo,
Count: count,
isHandle: tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
}
tbl.Columns[col.ID] = col
}
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2 changes: 1 addition & 1 deletion statistics/handle.go
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Expand Up @@ -258,7 +258,7 @@ func (h *Handle) LoadNeededHistograms() error {
if err != nil {
return errors.Trace(err)
}
tbl.Columns[c.ID] = &Column{Histogram: *hg, Info: c.Info, CMSketch: cms, Count: int64(hg.totalRowCount())}
tbl.Columns[c.ID] = &Column{Histogram: *hg, Info: c.Info, CMSketch: cms, Count: int64(hg.totalRowCount()), isHandle: c.isHandle}
h.UpdateTableStats([]*Table{tbl}, nil)
histogramNeededColumns.delete(col)
}
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5 changes: 3 additions & 2 deletions statistics/histogram.go
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Expand Up @@ -720,8 +720,9 @@ func (e *ErrorRate) merge(rate *ErrorRate) {
type Column struct {
Histogram
*CMSketch
Count int64
Info *model.ColumnInfo
Count int64
Info *model.ColumnInfo
isHandle bool
ErrorRate
}

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2 changes: 1 addition & 1 deletion statistics/selectivity.go
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Expand Up @@ -180,7 +180,7 @@ func (coll *HistColl) Selectivity(ctx sessionctx.Context, exprs []expression.Exp
return 0, errors.Trace(err)
}
sets = append(sets, &exprSet{tp: colType, ID: id, mask: maskCovered, ranges: ranges, numCols: 1})
if mysql.HasPriKeyFlag(colInfo.Info.Flag) {
if colInfo.isHandle {
sets[len(sets)-1].tp = pkType
}
}
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17 changes: 17 additions & 0 deletions statistics/selectivity_test.go
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Expand Up @@ -324,6 +324,23 @@ func (s *testSelectivitySuite) TestEstimationForUnknownValues(c *C) {
c.Assert(count, Equals, 0.0)
}

func (s *testSelectivitySuite) TestPrimaryKeySelectivity(c *C) {
testKit := testkit.NewTestKit(c, s.store)
testKit.MustExec("use test")
testKit.MustExec("drop table if exists t")
testKit.MustExec("create table t(a char(10) primary key, b int)")
testKit.MustQuery(`explain select * from t where a > "t"`).Check(testkit.Rows(
"IndexLookUp_10 3333.33 root ",
"├─IndexScan_8 3333.33 cop table:t, index:a, range:(\"t\",+inf], keep order:false, stats:pseudo",
"└─TableScan_9 3333.33 cop table:t, keep order:false, stats:pseudo"))

testKit.MustExec("drop table t")
testKit.MustExec("create table t(a int primary key, b int)")
testKit.MustQuery(`explain select * from t where a > 1`).Check(testkit.Rows(
"TableReader_6 3333.33 root data:TableScan_5",
"└─TableScan_5 3333.33 cop table:t, range:(1,+inf], keep order:false, stats:pseudo"))
}

func BenchmarkSelectivity(b *testing.B) {
c := &C{}
s := &testSelectivitySuite{}
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4 changes: 3 additions & 1 deletion statistics/table.go
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Expand Up @@ -188,6 +188,7 @@ func (h *Handle) columnStatsFromStorage(row chunk.Row, table *Table, tableInfo *
Info: colInfo,
Count: count + nullCount,
ErrorRate: errorRate,
isHandle: tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
}
break
}
Expand All @@ -206,6 +207,7 @@ func (h *Handle) columnStatsFromStorage(row chunk.Row, table *Table, tableInfo *
CMSketch: cms,
Count: int64(hg.totalRowCount()),
ErrorRate: errorRate,
isHandle: tableInfo.PKIsHandle && mysql.HasPriKeyFlag(colInfo.Flag),
}
break
}
Expand Down Expand Up @@ -610,7 +612,7 @@ func PseudoTable(tblInfo *model.TableInfo) *Table {
}
for _, col := range tblInfo.Columns {
if col.State == model.StatePublic {
t.Columns[col.ID] = &Column{Info: col}
t.Columns[col.ID] = &Column{Info: col, isHandle: tblInfo.PKIsHandle && mysql.HasPriKeyFlag(col.Flag)}
}
}
for _, idx := range tblInfo.Indices {
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