planner: don't push down some conditions to projections (#37992) (#38596

)

ref #35623

expression/util.go

@@ -139,9 +139,10 @@ func ExtractCorColumns(expr Expression) (cols []*CorrelatedColumn) {
 // It's often observed that the pattern of the caller like this:
 //
 // cols := ExtractColumns(...)
-// for _, col := range cols {
-//     if xxx(col) {...}
-// }
+//
+//	for _, col := range cols {
+//	    if xxx(col) {...}
+//	}
 //
 // Provide an additional filter argument, this can be done in one step.
 // To avoid allocation for cols that not need.
@@ -379,6 +380,17 @@ func setExprColumnInOperand(expr Expression) Expression {
 	return expr
 }
 
+// ColumnSubstitute4PPD substitutes the columns in filter to expressions in select fields.
+// Only used for predicate push down to projection. Some columns can not be substituted for some reasons.
+// So we should return the bool value to indicate some expressions can not be pushed down.
+// e.g. CREATE TABLE t3(c0 INT, primary key(c0));
+// SELECT v2.c0 FROM (select 1 as c0 from t3) v2 WHERE (v2.c0)like(True);
+// The cond `(v2.c0)like(True)` can not be substituted when the new collation enable. So we shouldn't push the cond down to the projection.
+func ColumnSubstitute4PPD(expr Expression, schema *Schema, newExprs []Expression) (bool, Expression) {
+	substituted, resExpr := ColumnSubstituteImpl(expr, schema, newExprs)
+	return substituted, resExpr
+}
+
 // ColumnSubstitute substitutes the columns in filter to expressions in select fields.
 // e.g. select * from (select b as a from t) k where a < 10 => select * from (select b as a from t where b < 10) k.
 func ColumnSubstitute(expr Expression, schema *Schema, newExprs []Expression) Expression {
@@ -702,8 +714,9 @@ func ContainOuterNot(expr Expression) bool {
 // Input `not` means whether there is `not` outside `expr`
 //
 // eg.
-//    not(0+(t.a == 1 and t.b == 2)) returns true
-//    not(t.a) and not(t.b) returns false
+//
+//	not(0+(t.a == 1 and t.b == 2)) returns true
+//	not(t.a) and not(t.b) returns false
 func containOuterNot(expr Expression, not bool) bool {
 	if f, ok := expr.(*ScalarFunction); ok {
 		switch f.FuncName.L {

planner/cascades/transformation_rules.go

@@ -549,8 +549,9 @@ func (r *PushSelDownProjection) OnTransform(old *memo.ExprIter) (newExprs []*mem
 	canBePushed := make([]expression.Expression, 0, len(sel.Conditions))
 	canNotBePushed := make([]expression.Expression, 0, len(sel.Conditions))
 	for _, cond := range sel.Conditions {
-		if !expression.HasGetSetVarFunc(cond) {
-			canBePushed = append(canBePushed, expression.ColumnSubstitute(cond, projSchema, proj.Exprs))
+		substituted, newFilter := expression.ColumnSubstitute4PPD(cond, projSchema, proj.Exprs)
+		if substituted && !expression.HasGetSetVarFunc(newFilter) {
+			canBePushed = append(canBePushed, newFilter)
 		} else {
 			canNotBePushed = append(canNotBePushed, cond)
 		}

planner/core/integration_test.go

@@ -302,6 +302,33 @@ func TestIssue22828(t *testing.T) {
 	tk.MustGetErrMsg(`select group_concat((select concat(c,group_concat(c)) FROM t where xxx=xxx)) FROM t;`, "[planner:1054]Unknown column 'xxx' in 'where clause'")
 }
 
+func TestIssue35623(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec(`drop table if exists t1;`)
+	tk.MustExec(`drop view if exists v1;`)
+	tk.MustExec(`CREATE TABLE t1(c0 INT UNIQUE);`)
+	tk.MustExec("CREATE definer='root'@'localhost' VIEW v1(c0) AS SELECT 1 FROM t1;")
+	err := tk.ExecToErr("SELECT v1.c0 FROM v1 WHERE (true)LIKE(v1.c0);")
+	require.NoError(t, err)
+
+	err = tk.ExecToErr("SELECT v2.c0 FROM (select 1 as c0 from t1) v2 WHERE (v2.c0)like(True);")
+	require.NoError(t, err)
+}
+
+func TestIssue37971(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec(`drop table if exists t3;`)
+	tk.MustExec(`CREATE TABLE t3(c0 INT, primary key(c0));`)
+	err := tk.ExecToErr("SELECT v2.c0 FROM (select 1 as c0 from t3) v2 WHERE (v2.c0)like(True);")
+	require.NoError(t, err)
+}
+
 func TestJoinNotNullFlag(t *testing.T) {
 	store, clean := testkit.CreateMockStore(t)
 	defer clean()

planner/core/rule_predicate_push_down.go

@@ -418,8 +418,8 @@ func (p *LogicalProjection) PredicatePushDown(predicates []expression.Expression
 		}
 	}
 	for _, cond := range predicates {
-		newFilter := expression.ColumnSubstitute(cond, p.Schema(), p.Exprs)
-		if !expression.HasGetSetVarFunc(newFilter) {
+		substituted, newFilter := expression.ColumnSubstitute4PPD(cond, p.Schema(), p.Exprs)
+		if substituted && !expression.HasGetSetVarFunc(newFilter) {
 			canBePushed = append(canBePushed, newFilter)
 		} else {
 			canNotBePushed = append(canNotBePushed, cond)