planner: wrong execution when CTE meet non-correlated subquery

cmd/explaintest/r/cte.result

@@ -564,19 +564,18 @@ create table tpk1(c1 int primary key);
 insert into tpk1 values(1), (2), (3);
 explain with cte1 as (select c1 from tpk) select /*+ merge_join(dt1, dt2) */ * from tpk1 dt1 inner join cte1 dt2 inner join cte1 dt3 on dt1.c1 = dt2.c1 and dt2.c1 = dt3.c1;
 id	estRows	task	access object	operator info
-HashJoin_20	10000.00	root		inner join, equal:[eq(test.tpk.c1, test.tpk.c1)]
-├─Selection_29(Build)	6400.00	root		not(isnull(test.tpk.c1))
-│ └─CTEFullScan_30	8000.00	root	CTE:cte1 AS dt3	data:CTE_0
-└─MergeJoin_22(Probe)	8000.00	root		inner join, left key:test.tpk1.c1, right key:test.tpk.c1
-  ├─Sort_28(Build)	6400.00	root		test.tpk.c1
-  │ └─Selection_26	6400.00	root		not(isnull(test.tpk.c1))
-  │   └─CTEFullScan_27	8000.00	root	CTE:cte1 AS dt2	data:CTE_0
-  └─TableReader_24(Probe)	10000.00	root		data:TableFullScan_23
-    └─TableFullScan_23	10000.00	cop[tikv]	table:dt1	keep order:true, stats:pseudo
-CTE_0	8000.00	root		Non-Recursive CTE
-└─Selection_13(Seed Part)	8000.00	root		or(not(isnull(test.tpk.c1)), not(isnull(test.tpk.c1)))
-  └─TableReader_16	10000.00	root		data:TableFullScan_15
-    └─TableFullScan_15	10000.00	cop[tikv]	table:tpk	keep order:false, stats:pseudo
+HashJoin_19	12500.00	root		inner join, equal:[eq(test.tpk.c1, test.tpk.c1)]
+├─Selection_28(Build)	8000.00	root		not(isnull(test.tpk.c1))
+│ └─CTEFullScan_29	10000.00	root	CTE:cte1 AS dt3	data:CTE_0
+└─MergeJoin_21(Probe)	10000.00	root		inner join, left key:test.tpk1.c1, right key:test.tpk.c1
+  ├─Sort_27(Build)	8000.00	root		test.tpk.c1
+  │ └─Selection_25	8000.00	root		not(isnull(test.tpk.c1))
+  │   └─CTEFullScan_26	10000.00	root	CTE:cte1 AS dt2	data:CTE_0
+  └─TableReader_23(Probe)	10000.00	root		data:TableFullScan_22
+    └─TableFullScan_22	10000.00	cop[tikv]	table:dt1	keep order:true, stats:pseudo
+CTE_0	10000.00	root		Non-Recursive CTE
+└─TableReader_15(Seed Part)	10000.00	root		data:TableFullScan_14
+  └─TableFullScan_14	10000.00	cop[tikv]	table:tpk	keep order:false, stats:pseudo
 with cte1 as (select c1 from tpk) select /*+ merge_join(dt1, dt2) */ * from tpk1 dt1 inner join cte1 dt2 inner join cte1 dt3 on dt1.c1 = dt2.c1 and dt2.c1 = dt3.c1;
 c1	c1	c1
 1	1	1

cmd/explaintest/r/explain_cte.result

@@ -60,12 +60,11 @@ CTE_0	2.00	root		Recursive CTE
     └─CTETable_17	1.00	root		Scan on CTE_0
 explain with cte(a) as (with recursive cte1(a) as (select 1 union select a + 1 from cte1 where a < 10) select * from cte1) select * from cte t1, cte t2;
 id	estRows	task	access object	operator info
-HashJoin_26	2.56	root		CARTESIAN inner join
-├─CTEFullScan_29(Build)	1.60	root	CTE:cte AS t2	data:CTE_0
-└─CTEFullScan_28(Probe)	1.60	root	CTE:cte AS t1	data:CTE_0
-CTE_0	1.60	root		Non-Recursive CTE
-└─Selection_21(Seed Part)	1.60	root		1
-  └─CTEFullScan_23	2.00	root	CTE:cte1	data:CTE_1
+HashJoin_25	4.00	root		CARTESIAN inner join
+├─CTEFullScan_28(Build)	2.00	root	CTE:cte AS t2	data:CTE_0
+└─CTEFullScan_27(Probe)	2.00	root	CTE:cte AS t1	data:CTE_0
+CTE_0	2.00	root		Non-Recursive CTE
+└─CTEFullScan_22(Seed Part)	2.00	root	CTE:cte1	data:CTE_1
 CTE_1	2.00	root		Recursive CTE
 ├─Projection_16(Seed Part)	1.00	root		1->Column#2
 │ └─TableDual_17	1.00	root		rows:1
@@ -91,15 +90,13 @@ CTE_1	8001.00	root		Recursive CTE
     └─CTETable_33	10000.00	root		Scan on CTE_1
 explain with q(a,b) as (select * from t1) select /*+ merge(q) no_merge(q1) */ * from q, q q1 where q.a=1 and q1.a=2;
 id	estRows	task	access object	operator info
-HashJoin_19	40960000.00	root		CARTESIAN inner join
-├─Selection_23(Build)	6400.00	root		eq(test.t1.c1, 2)
-│ └─CTEFullScan_24	8000.00	root	CTE:q AS q1	data:CTE_0
-└─Selection_21(Probe)	6400.00	root		eq(test.t1.c1, 1)
-  └─CTEFullScan_22	8000.00	root	CTE:q	data:CTE_0
-CTE_0	8000.00	root		Non-Recursive CTE
-└─Selection_11(Seed Part)	8000.00	root		or(eq(test.t1.c1, 1), eq(test.t1.c1, 2))
-  └─TableReader_14	10000.00	root		data:TableFullScan_13
-    └─TableFullScan_13	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo
+HashJoin_15	2.56	root		CARTESIAN inner join
+├─Selection_19(Build)	1.60	root		eq(test.t1.c1, 2)
+│ └─CTEFullScan_20	2.00	root	CTE:q AS q1	data:CTE_0
+└─Selection_17(Probe)	1.60	root		eq(test.t1.c1, 1)
+  └─CTEFullScan_18	2.00	root	CTE:q	data:CTE_0
+CTE_0	2.00	root		Non-Recursive CTE
+└─Batch_Point_Get_12(Seed Part)	2.00	root	table:t1	handle:[1 2], keep order:false, desc:false
 explain with recursive cte(a,b) as (select 1, concat('a', 1) union select a+1, concat(b, 1) from cte where a < 5) select * from cte;
 id	estRows	task	access object	operator info
 CTEFullScan_17	2.00	root	CTE:cte	data:CTE_0
@@ -458,14 +455,14 @@ select v1.tps v1_tps,v2.tps v2_tps
 from version1 v1, version2 v2
 where v1.bench_type =v2.bench_type;
 id	estRows	task	access object	operator info
-HashJoin	8000.00	root		inner join, equal:[eq(test.t1.bench_type, test.t1.bench_type)]
-├─Selection(Build)	6400.00	root		eq(test.t1.version, "6.0.0"), not(isnull(test.t1.bench_type))
-│ └─CTEFullScan	8000.00	root	CTE:all_data	data:CTE_0
-└─Selection(Probe)	6400.00	root		eq(test.t1.version, "5.4.0"), not(isnull(test.t1.bench_type))
-  └─CTEFullScan	8000.00	root	CTE:all_data	data:CTE_0
-CTE_0	8000.00	root		Non-Recursive CTE
-└─Selection(Seed Part)	8000.00	root		or(and(eq(test.t1.version, "5.4.0"), not(isnull(test.t1.bench_type))), and(eq(test.t1.version, "6.0.0"), not(isnull(test.t1.bench_type))))
-  └─TableReader	10000.00	root		data:TableFullScan
+HashJoin	19.97	root		inner join, equal:[eq(test.t1.bench_type, test.t1.bench_type)]
+├─Selection(Build)	15.98	root		eq(test.t1.version, "6.0.0"), not(isnull(test.t1.bench_type))
+│ └─CTEFullScan	19.97	root	CTE:all_data	data:CTE_0
+└─Selection(Probe)	15.98	root		eq(test.t1.version, "5.4.0"), not(isnull(test.t1.bench_type))
+  └─CTEFullScan	19.97	root	CTE:all_data	data:CTE_0
+CTE_0	19.97	root		Non-Recursive CTE
+└─TableReader(Seed Part)	19.97	root		data:Selection
+  └─Selection	19.97	cop[tikv]		or(and(eq(test.t1.version, "5.4.0"), not(isnull(test.t1.bench_type))), and(eq(test.t1.version, "6.0.0"), not(isnull(test.t1.bench_type))))
     └─TableFullScan	10000.00	cop[tikv]	table:t1	keep order:false, stats:pseudo
 drop table if exists tbl;
 create table tbl (id int);

executor/explain_test.go

@@ -371,7 +371,7 @@ func TestCheckActRowsWithUnistore(t *testing.T) {
 		},
 		{
 			sql:      "with cte(a) as (select a from t_unistore_act_rows) select (select 1 from cte limit 1) from cte;",
-			expected: []string{"4", "4", "4", "4", "4"},
+			expected: []string{"4", "1", "1", "1", "4", "4", "4", "4", "4"},
 		},
 		{
 			sql:      "select a, row_number() over (partition by b) from t_unistore_act_rows;",

planner/core/expression_rewriter.go

@@ -1053,7 +1053,7 @@ func (er *expressionRewriter) handleScalarSubquery(ctx context.Context, v *ast.S
 		noDecorrelate = false
 	}
 
-	if er.b.disableSubQueryPreprocessing || len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 {
+	if er.b.disableSubQueryPreprocessing || len(ExtractCorrelatedCols4LogicalPlan(np)) > 0 || hasCTEConsumerInSubPlan(np) {
 		er.p = er.b.buildApplyWithJoinType(er.p, np, LeftOuterJoin, noDecorrelate)
 		if np.Schema().Len() > 1 {
 			newCols := make([]expression.Expression, 0, np.Schema().Len())
@@ -1111,6 +1111,18 @@ func (er *expressionRewriter) handleScalarSubquery(ctx context.Context, v *ast.S
 	return v, true
 }
 
+func hasCTEConsumerInSubPlan(p LogicalPlan) bool {
+	if _, ok := p.(*LogicalCTE); ok {
+		return true
+	}
+	for _, child := range p.Children() {
+		if hasCTEConsumerInSubPlan(child) {
+			return true
+		}
+	}
+	return false
+}
+
 func initConstantRepertoire(c *expression.Constant) {
 	c.SetRepertoire(expression.ASCII)
 	if c.GetType().EvalType() == types.ETString {

planner/core/issuetest/BUILD.bazel

@@ -9,7 +9,7 @@ go_test(
     ],
     flaky = True,
     race = "on",
-    shard_count = 3,
+    shard_count = 4,
     deps = [
         "//parser",
         "//planner",

planner/core/issuetest/planner_issue_test.go

@@ -92,3 +92,17 @@ func TestIssue43645(t *testing.T) {
 	rs := tk.MustQuery("WITH tmp AS (SELECT t2.* FROM t2) select (SELECT tmp.col1 FROM tmp WHERE tmp.id=t1.id ) col1, (SELECT tmp.col2 FROM tmp WHERE tmp.id=t1.id ) col2, (SELECT tmp.col3 FROM tmp WHERE tmp.id=t1.id ) col3 from t1;")
 	rs.Sort().Check(testkit.Rows("a aa aaa", "b bb bbb", "c cc ccc"))
 }
+
+func TestIssue44051(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test")
+	tk.MustExec("CREATE TABLE t1(id int,col1 varchar(10),col2 varchar(10),col3 varchar(10));")
+	tk.MustExec("CREATE TABLE t2(id int,col1 varchar(10),col2 varchar(10),col3 varchar(10));")
+	tk.MustExec("INSERT INTO t1 values(1,NULL,NULL,null),(2,NULL,NULL,null),(3,NULL,NULL,null);")
+	tk.MustExec("INSERT INTO t2 values(1,'a','aa','aaa'),(2,'b','bb','bbb'),(3,'c','cc','ccc');")
+
+	rs := tk.MustQuery("WITH tmp AS (SELECT t2.* FROM t2) SELECT * FROM t1 WHERE t1.id = (select id from tmp where id = 1) or t1.id = (select id from tmp where id = 2) or t1.id = (select id from tmp where id = 3)")
+	rs.Sort().Check(testkit.Rows("1 <nil> <nil> <nil>", "2 <nil> <nil> <nil>", "3 <nil> <nil> <nil>"))
+}

planner/core/planbuilder.go

@@ -975,12 +975,28 @@ func (b *PlanBuilder) buildSet(ctx context.Context, v *ast.SetStmt) (Plan, error
 				char, col := b.ctx.GetSessionVars().GetCharsetInfo()
 				vars.Value = ast.NewValueExpr(cn.Name.Name.O, char, col)
 			}
-			mockTablePlan := LogicalTableDual{}.Init(b.ctx, b.getSelectOffset())
+			mockTablePlan := LogicalTableDual{RowCount: 1}.Init(b.ctx, b.getSelectOffset())
 			var err error
-			assign.Expr, _, err = b.rewrite(ctx, vars.Value, mockTablePlan, nil, true)
+			var possiblePlan LogicalPlan
+			assign.Expr, possiblePlan, err = b.rewrite(ctx, vars.Value, mockTablePlan, nil, true)
 			if err != nil {
 				return nil, err
 			}
+			if _, ok := possiblePlan.(*LogicalTableDual); !ok {
+				physicalPlan, _, err := DoOptimize(ctx, b.ctx, b.optFlag, possiblePlan)
+				if err != nil {
+					return nil, err
+				}
+				row, err := EvalSubqueryFirstRow(ctx, physicalPlan, b.is, b.ctx)
+				if err != nil {
+					return nil, err
+				}
+				constant := &expression.Constant{
+					Value:   row[0],
+					RetType: assign.Expr.GetType(),
+				}
+				assign.Expr = constant
+			}
 		} else {
 			assign.IsDefault = true
 		}

planner/core/stats.go

@@ -1109,7 +1109,7 @@ func (p *LogicalCTE) DeriveStats(_ []*property.StatsInfo, selfSchema *expression
 			newSel.SetChildren(p.cte.seedPartLogicalPlan)
 			p.cte.seedPartLogicalPlan = newSel
 		}
-		p.cte.seedPartPhysicalPlan, _, err = DoOptimize(context.TODO(), p.ctx, p.cte.optFlag, p.cte.seedPartLogicalPlan)
+		p.cte.seedPartPhysicalPlan, _, err = DoOptimize(context.TODO(), p.ctx, p.cte.optFlag|flagPredicatePushDown, p.cte.seedPartLogicalPlan)
 		if err != nil {
 			return nil, err
 		}