plan: fix bug of stats count (pingcap#5775)

doerjiayi · Feb 6, 2018 · 4e55470 · 4e55470
1 parent 8cc9e45
commit 4e55470
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Showing 5 changed files with 12 additions and 9 deletions.
diff --git a/expression/integration_test.go b/expression/integration_test.go
@@ -2620,8 +2620,8 @@ func (s *testIntegrationSuite) TestCompareBuiltin(c *C) {
 	tk.MustExec("drop table if exists t;")
 	tk.MustExec("create table t(a date)")
 	result = tk.MustQuery("desc select a = a from t")
-	result.Check(testkit.Rows("TableScan_4   cop table:t, range:[-inf,+inf], keep order:false 8000",
-		"TableReader_5 Projection_3  root data:TableScan_4 8000",
+	result.Check(testkit.Rows("TableScan_4   cop table:t, range:[-inf,+inf], keep order:false 10000",
+		"TableReader_5 Projection_3  root data:TableScan_4 10000",
 		"Projection_3  TableReader_5 root eq(test.t.a, test.t.a) 8000"))
 
 	// for interval

diff --git a/plan/cbo_test.go b/plan/cbo_test.go
@@ -386,9 +386,8 @@ func (s *testAnalyzeSuite) TestOutdatedAnalyze(c *C) {
 	testKit.MustExec("insert into t select * from t")
 	h.DumpStatsDeltaToKV()
 	c.Assert(h.Update(dom.InfoSchema()), IsNil)
-	// FIXME: The count for table scan is wrong.
 	testKit.MustQuery("explain select * from t where a <= 5 and b <= 5").Check(testkit.Rows(
-		"TableScan_5 Selection_6  cop table:t, range:[-inf,+inf], keep order:false 28.799999999999997",
+		"TableScan_5 Selection_6  cop table:t, range:[-inf,+inf], keep order:false 80",
 		"Selection_6  TableScan_5 cop le(test.t.a, 5), le(test.t.b, 5) 28.799999999999997",
 		"TableReader_7   root data:Selection_6 28.799999999999997",
 	))

diff --git a/plan/logical_plans.go b/plan/logical_plans.go
@@ -282,6 +282,9 @@ type DataSource struct {
 	// pushedDownConds are the conditions that will be pushed down to coprocessor.
 	pushedDownConds []expression.Expression
 
+	// statsAfterSelect is the statsInfo for dataSource and selection.
+	statsAfterSelect *statsInfo
+
 	statisticTable *statistics.Table
 
 	// availableIndices is used for storing result of avalableIndices function.

diff --git a/plan/physical_plan_builder.go b/plan/physical_plan_builder.go
@@ -429,7 +429,7 @@ func (is *PhysicalIndexScan) addPushedDownSelection(copTask *copTask, p *DataSou
 		}
 		if tableConds != nil {
 			copTask.finishIndexPlan()
-			tableSel := PhysicalSelection{Conditions: tableConds}.init(is.ctx, p.stats.scaleByExpectCnt(expectedCnt))
+			tableSel := PhysicalSelection{Conditions: tableConds}.init(is.ctx, p.statsAfterSelect.scaleByExpectCnt(expectedCnt))
 			tableSel.SetChildren(copTask.tablePlan)
 			copTask.tablePlan = tableSel
 			copTask.cst += copTask.count() * cpuFactor
@@ -586,15 +586,15 @@ func (ds *DataSource) convertToTableScan(prop *requiredProp) (task task, err err
 		}
 		ts.KeepOrder = true
 		copTask.keepOrder = true
-		ts.addPushedDownSelection(copTask, ds.stats.scaleByExpectCnt(prop.expectedCnt))
+		ts.addPushedDownSelection(copTask, ds.statsAfterSelect.scaleByExpectCnt(prop.expectedCnt))
 	} else {
 		expectedCnt := math.MaxFloat64
 		if prop.isEmpty() {
 			expectedCnt = prop.expectedCnt
 		} else {
 			return invalidTask, nil
 		}
-		ts.addPushedDownSelection(copTask, ds.stats.scaleByExpectCnt(expectedCnt))
+		ts.addPushedDownSelection(copTask, ds.statsAfterSelect.scaleByExpectCnt(expectedCnt))
 	}
 	if prop.taskTp == rootTaskType {
 		task = finishCopTask(task, ds.ctx)

diff --git a/plan/stats.go b/plan/stats.go
@@ -92,6 +92,7 @@ func (ds *DataSource) getStatsByFilter(conds expression.CNFExprs) *statsInfo {
 			profile.cardinality[i] = profile.count * distinctFactor
 		}
 	}
+	ds.stats = profile
 	selectivity, err := ds.statisticTable.Selectivity(ds.ctx, conds)
 	if err != nil {
 		log.Warnf("An error happened: %v, we have to use the default selectivity", err.Error())
@@ -105,8 +106,8 @@ func (ds *DataSource) deriveStats() *statsInfo {
 	for i, expr := range ds.pushedDownConds {
 		ds.pushedDownConds[i] = expression.PushDownNot(expr, false, nil)
 	}
-	ds.stats = ds.getStatsByFilter(ds.pushedDownConds)
-	return ds.stats
+	ds.statsAfterSelect = ds.getStatsByFilter(ds.pushedDownConds)
+	return ds.statsAfterSelect
 }
 
 func (p *LogicalSelection) deriveStats() *statsInfo {