optimize stats when table not flushed yet

pkg/sql/plan/apply_indices.go

@@ -399,18 +399,22 @@ func (builder *QueryBuilder) applyIndicesForFiltersRegularIndex(nodeID int32, no
 		}
 	}
 
-	if catalog.IsFakePkName(node.TableDef.Pkey.PkeyColName) {
-		// for cluster by table, make it less prone to go index
-		if node.Stats.Selectivity >= InFilterSelectivityLimit/2 || node.Stats.Outcnt >= InFilterCardLimitNonPK {
+	//default stats means this table maybe not flushed yet, then we don't skip the index
+	ignoreStats := IsDefaultStats(node.Stats)
+	if !ignoreStats {
+		if catalog.IsFakePkName(node.TableDef.Pkey.PkeyColName) {
+			// for cluster by table, make it less prone to go index
+			if node.Stats.Selectivity >= InFilterSelectivityLimit/2 || node.Stats.Outcnt >= InFilterCardLimitNonPK {
+				return nodeID
+			}
+		}
+		if node.Stats.Selectivity > InFilterSelectivityLimit || node.Stats.Outcnt > float64(GetInFilterCardLimitOnPK(builder.compCtx.GetProcess().GetService(), node.Stats.TableCnt)) {
 			return nodeID
 		}
 	}
-	if node.Stats.Selectivity > InFilterSelectivityLimit || node.Stats.Outcnt > float64(GetInFilterCardLimitOnPK(builder.compCtx.GetProcess().GetService(), node.Stats.TableCnt)) {
-		return nodeID
-	}
 
 	// Apply unique/secondary indices for point select
-	idxToChoose, filterIdx := builder.getMostSelectiveIndexForPointSelect(indexes, node)
+	idxToChoose, filterIdx := builder.getMostSelectiveIndexForPointSelect(indexes, node, ignoreStats)
 	if idxToChoose != -1 {
 		retID, idxTableNodeID := builder.applyIndexJoin(indexes[idxToChoose], node, EqualIndexCondition, filterIdx, scanSnapshot)
 		builder.applyExtraFiltersOnIndex(indexes[idxToChoose], node, builder.qry.Nodes[idxTableNodeID], filterIdx)
@@ -848,7 +852,7 @@ func (builder *QueryBuilder) applyIndexJoin(idxDef *IndexDef, node *plan.Node, f
 	return joinNodeID, idxTableNodeID
 }
 
-func (builder *QueryBuilder) getMostSelectiveIndexForPointSelect(indexes []*IndexDef, node *plan.Node) (int, []int32) {
+func (builder *QueryBuilder) getMostSelectiveIndexForPointSelect(indexes []*IndexDef, node *plan.Node, ignoreStats bool) (int, []int32) {
 	currentSel := 1.0
 	currentIdx := -1
 	savedFilterIdx := make([]int32, 0)
@@ -889,7 +893,7 @@ func (builder *QueryBuilder) getMostSelectiveIndexForPointSelect(indexes []*Inde
 			}
 			filterIdx = append(filterIdx, idx)
 			filter := node.FilterList[idx]
-			if filter.Selectivity <= InFilterSelectivityLimit && node.Stats.TableCnt*filter.Selectivity <= float64(GetInFilterCardLimitOnPK(builder.compCtx.GetProcess().GetService(), node.Stats.TableCnt)) {
+			if ignoreStats || (filter.Selectivity <= InFilterSelectivityLimit && node.Stats.TableCnt*filter.Selectivity <= float64(GetInFilterCardLimitOnPK(builder.compCtx.GetProcess().GetService(), node.Stats.TableCnt))) {
 				usePartialIndex = true
 			}
 		}

pkg/sql/plan/stats.go

@@ -1415,6 +1415,10 @@ func DefaultBigStats() *plan.Stats {
 	return stats
 }
 
+func IsDefaultStats(stats *plan.Stats) bool {
+	return stats.Cost == 1000 && stats.TableCnt == 1000 && stats.Outcnt == 1000 && stats.Selectivity == 1 && stats.BlockNum == 1 && stats.Rowsize == 100
+}
+
 func DefaultStats() *plan.Stats {
 	stats := new(Stats)
 	stats.TableCnt = 1000

test/distributed/cases/optimizer/index.result

@@ -272,4 +272,18 @@ drop table t1;
 create table t1(a bigint, b bigint default null, c int, primary key(a), key(b));
 insert into t1(a,b,c) select result,result%10, result from generate_series(1,3000000)g;
 delete from t1 where b = 1;
+drop table t1;
+create table t1(c1 int, c2 int, c3 int, key(c1));
+explain select * from t1 where c1=1;
+TP QUERY PLAN
+Project
+  ->  Join
+        Join Type: INDEX
+        Join Cond: (t1.__mo_fake_pk_col = #[1,0])
+        Runtime Filter Build: #[-1,0]
+        ->  Table Scan on d1.t1 [ForceOneCN]
+              Filter Cond: (t1.c1 = 1)
+              Runtime Filter Probe: t1.__mo_fake_pk_col
+        ->  Index Table Scan on t1.c1 [ForceOneCN]
+              Filter Cond: prefix_eq(#[0,0])
 drop database d1;

test/distributed/cases/optimizer/index.test

@@ -124,4 +124,8 @@ drop table t1;
 create table t1(a bigint, b bigint default null, c int, primary key(a), key(b));
 insert into t1(a,b,c) select result,result%10, result from generate_series(1,3000000)g;
 delete from t1 where b = 1;
-drop database d1;
+drop table t1;
+create table t1(c1 int, c2 int, c3 int, key(c1));
+-- @separator:table
+explain select * from t1 where c1=1;
+drop database d1;