planner: not to generate partial agg when cop task has root condition…

planner/core/integration_test.go

@@ -301,6 +301,41 @@ func (s *testIntegrationSuite) TestSelPushDownTiFlash(c *C) {
 	))
 }
 
+func (s *testIntegrationSuite) TestIssue15110(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists crm_rd_150m")
+	tk.MustExec(`CREATE TABLE crm_rd_150m (
+	product varchar(256) DEFAULT NULL,
+		uks varchar(16) DEFAULT NULL,
+		brand varchar(256) DEFAULT NULL,
+		cin varchar(16) DEFAULT NULL,
+		created_date timestamp NULL DEFAULT NULL,
+		quantity int(11) DEFAULT NULL,
+		amount decimal(11,0) DEFAULT NULL,
+		pl_date timestamp NULL DEFAULT NULL,
+		customer_first_date timestamp NULL DEFAULT NULL,
+		recent_date timestamp NULL DEFAULT NULL
+	) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;`)
+
+	// Create virtual tiflash replica info.
+	dom := domain.GetDomain(tk.Se)
+	is := dom.InfoSchema()
+	db, exists := is.SchemaByName(model.NewCIStr("test"))
+	c.Assert(exists, IsTrue)
+	for _, tblInfo := range db.Tables {
+		if tblInfo.Name.L == "crm_rd_150m" {
+			tblInfo.TiFlashReplica = &model.TiFlashReplicaInfo{
+				Count:     1,
+				Available: true,
+			}
+		}
+	}
+
+	tk.MustExec("set @@session.tidb_isolation_read_engines = 'tiflash'")
+	tk.MustExec("explain SELECT count(*) FROM crm_rd_150m dataset_48 WHERE (CASE WHEN (month(dataset_48.customer_first_date)) <= 30 THEN '新客' ELSE NULL END) IS NOT NULL;")
+}
+
 func (s *testIntegrationSuite) TestReadFromStorageHint(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

planner/core/planbuilder.go

@@ -612,7 +612,7 @@ func (b *PlanBuilder) getPossibleAccessPaths(indexHints []*ast.IndexHint, tblInf
 
 func (b *PlanBuilder) filterPathByIsolationRead(paths []*accessPath, dbName model.CIStr) ([]*accessPath, error) {
 	// TODO: filter paths with isolation read locations.
-	if dbName.L == mysql.SystemDB {
+	if dbName.L == mysql.SystemDB || dbName.L == "information_schema" || dbName.L == "performance_schema" {
 		return paths, nil
 	}
 	cfgIsolationEngines := set.StringSet{}

planner/core/task.go

@@ -522,7 +522,7 @@ func (p *PhysicalLimit) attach2Task(tasks ...task) task {
 	if cop, ok := t.(*copTask); ok {
 		// For double read which requires order being kept, the limit cannot be pushed down to the table side,
 		// because handles would be reordered before being sent to table scan.
-		if !cop.keepOrder || !cop.indexPlanFinished || cop.indexPlan == nil {
+		if (!cop.keepOrder || !cop.indexPlanFinished || cop.indexPlan == nil) && len(cop.rootTaskConds) == 0 {
 			// When limit is pushed down, we should remove its offset.
 			newCount := p.Offset + p.Count
 			childProfile := cop.plan().statsInfo()
@@ -654,7 +654,7 @@ func (p *PhysicalTopN) getPushedDownTopN(childPlan PhysicalPlan) *PhysicalTopN {
 func (p *PhysicalTopN) attach2Task(tasks ...task) task {
 	t := tasks[0].copy()
 	inputCount := t.count()
-	if copTask, ok := t.(*copTask); ok && p.canPushDown() {
+	if copTask, ok := t.(*copTask); ok && p.canPushDown() && len(copTask.rootTaskConds) == 0 {
 		// If all columns in topN are from index plan, we push it to index plan, otherwise we finish the index plan and
 		// push it to table plan.
 		var pushedDownTopN *PhysicalTopN
@@ -824,7 +824,7 @@ func (p *PhysicalStreamAgg) attach2Task(tasks ...task) task {
 		// The `doubleReadNeedProj` is always set if the double read needs to keep order. So we just use it to decided
 		// whether the following plan is double read with order reserved.
 		copToFlash := isFlashCopTask(cop)
-		if !cop.doubleReadNeedProj {
+		if !cop.doubleReadNeedProj && len(cop.rootTaskConds) == 0 {
 			partialAgg, finalAgg := p.newPartialAggregate(copToFlash)
 			if partialAgg != nil {
 				if cop.tablePlan != nil {
@@ -901,29 +901,34 @@ func (p *PhysicalHashAgg) attach2Task(tasks ...task) task {
 	t := tasks[0].copy()
 	inputRows := t.count()
 	if cop, ok := t.(*copTask); ok {
-		// copToFlash means whether the cop task is running on flash storage
-		copToFlash := isFlashCopTask(cop)
-		partialAgg, finalAgg := p.newPartialAggregate(copToFlash)
-		if partialAgg != nil {
-			if cop.tablePlan != nil {
-				cop.finishIndexPlan()
-				partialAgg.SetChildren(cop.tablePlan)
-				cop.tablePlan = partialAgg
-			} else {
-				partialAgg.SetChildren(cop.indexPlan)
-				cop.indexPlan = partialAgg
+		if len(cop.rootTaskConds) == 0 {
+			// copToFlash means whether the cop task is running on flash storage
+			copToFlash := isFlashCopTask(cop)
+			partialAgg, finalAgg := p.newPartialAggregate(copToFlash)
+			if partialAgg != nil {
+				if cop.tablePlan != nil {
+					cop.finishIndexPlan()
+					partialAgg.SetChildren(cop.tablePlan)
+					cop.tablePlan = partialAgg
+				} else {
+					partialAgg.SetChildren(cop.indexPlan)
+					cop.indexPlan = partialAgg
+				}
+				cop.addCost(p.GetCost(inputRows, false))
 			}
-			cop.addCost(p.GetCost(inputRows, false))
+			// In `newPartialAggregate`, we are using stats of final aggregation as stats
+			// of `partialAgg`, so the network cost of transferring result rows of `partialAgg`
+			// to TiDB is normally under-estimated for hash aggregation, since the group-by
+			// column may be independent of the column used for region distribution, so a closer
+			// estimation of network cost for hash aggregation may multiply the number of
+			// regions involved in the `partialAgg`, which is unknown however.
+			t = finishCopTask(p.ctx, cop)
+			inputRows = t.count()
+			attachPlan2Task(finalAgg, t)
+		} else {
+			t = finishCopTask(p.ctx, cop)
+			attachPlan2Task(p, t)
 		}
-		// In `newPartialAggregate`, we are using stats of final aggregation as stats
-		// of `partialAgg`, so the network cost of transferring result rows of `partialAgg`
-		// to TiDB is normally under-estimated for hash aggregation, since the group-by
-		// column may be independent of the column used for region distribution, so a closer
-		// estimation of network cost for hash aggregation may multiply the number of
-		// regions involved in the `partialAgg`, which is unknown however.
-		t = finishCopTask(p.ctx, cop)
-		inputRows = t.count()
-		attachPlan2Task(finalAgg, t)
 	} else {
 		attachPlan2Task(p, t)
 	}