plan: build separate required physical property for children

For logical operator which passes the required physical property
down to its children, make a copy for it instead of direct assignment
using the original pointer.

executor/merge_join_test.go

@@ -289,6 +289,18 @@ func (s *testSuite) TestMergeJoin(c *C) {
 	result.Check(testkit.Rows("1", "2", "3", "4", "5", "6", "7"))
 	result = tk.MustQuery("select /*+ TIDB_SMJ(a, b) */ a.c1 from t a , (select * from t1 limit 3) b where a.c1 = b.c1 order by b.c1;")
 	result.Check(testkit.Rows("1", "2", "3"))
+	// Test LogicalSelection under LogicalJoin.
+	result = tk.MustQuery("select /*+ TIDB_SMJ(a, b) */ a.c1 from t a , (select * from t1 limit 3) b where a.c1 = b.c1 and b.c1 is not null order by b.c1;")
+	result.Check(testkit.Rows("1", "2", "3"))
+	tk.MustExec("begin;")
+	// Test LogicalLock under LogicalJoin.
+	result = tk.MustQuery("select /*+ TIDB_SMJ(a, b) */ a.c1 from t a , (select * from t1 for update) b where a.c1 = b.c1 order by a.c1;")
+	result.Check(testkit.Rows("1", "2", "3", "4", "5", "6", "7"))
+	// Test LogicalUnionScan under LogicalJoin.
+	tk.MustExec("insert into t1 values(8);")
+	result = tk.MustQuery("select /*+ TIDB_SMJ(a, b) */ a.c1 from t a , t1 b where a.c1 = b.c1;")
+	result.Check(testkit.Rows("1", "2", "3", "4", "5", "6", "7"))
+	tk.MustExec("rollback;")
 
 	plannercore.AllowCartesianProduct = false
 	_, err := tk.Exec("select /*+ TIDB_SMJ(t,t1) */ * from t, t1")

planner/core/exhaust_physical_plans.go

@@ -29,7 +29,8 @@ import (
 )
 
 func (p *LogicalUnionScan) exhaustPhysicalPlans(prop *property.PhysicalProperty) []PhysicalPlan {
-	us := PhysicalUnionScan{Conditions: p.conditions}.init(p.ctx, p.stats, prop)
+	childProp := prop.Clone()
+	us := PhysicalUnionScan{Conditions: p.conditions}.init(p.ctx, p.stats, childProp)
 	return []PhysicalPlan{us}
 }
 
@@ -846,9 +847,10 @@ func (la *LogicalAggregation) exhaustPhysicalPlans(prop *property.PhysicalProper
 }
 
 func (p *LogicalSelection) exhaustPhysicalPlans(prop *property.PhysicalProperty) []PhysicalPlan {
+	childProp := prop.Clone()
 	sel := PhysicalSelection{
 		Conditions: p.Conditions,
-	}.init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), prop)
+	}.init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), childProp)
 	return []PhysicalPlan{sel}
 }
 
@@ -869,9 +871,10 @@ func (p *LogicalLimit) exhaustPhysicalPlans(prop *property.PhysicalProperty) []P
 }
 
 func (p *LogicalLock) exhaustPhysicalPlans(prop *property.PhysicalProperty) []PhysicalPlan {
+	childProp := prop.Clone()
 	lock := PhysicalLock{
 		Lock: p.Lock,
-	}.init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), prop)
+	}.init(p.ctx, p.stats.ScaleByExpectCnt(prop.ExpectedCnt), childProp)
 	return []PhysicalPlan{lock}
 }
 

planner/property/physical_property.go

@@ -101,3 +101,17 @@ func (p *PhysicalProperty) HashCode() []byte {
 func (p *PhysicalProperty) String() string {
 	return fmt.Sprintf("Prop{cols: %v, desc: %v, TaskTp: %s, expectedCount: %v}", p.Cols, p.Desc, p.TaskTp, p.ExpectedCnt)
 }
+
+// Clone returns a copy of PhysicalProperty. Currently, this function is only used to build new
+// required property for children plan in `exhaustPhysicalPlans`, so we don't copy `Enforced` field
+// because if `Enforced` is true, the `Cols` must be empty now, this makes `Enforced` meaningless
+// for children nodes.
+func (p *PhysicalProperty) Clone() *PhysicalProperty {
+	prop := &PhysicalProperty{
+		Cols:        p.Cols,
+		Desc:        p.Desc,
+		TaskTp:      p.TaskTp,
+		ExpectedCnt: p.ExpectedCnt,
+	}
+	return prop
+}