expression, planner: push cast down to control function with enum type. (#24542)

expression/builtin_cast.go

@@ -1811,6 +1811,7 @@ func BuildCastFunction4Union(ctx sessionctx.Context, expr Expression, tp *types.
 
 // BuildCastFunction builds a CAST ScalarFunction from the Expression.
 func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression) {
+	expr = TryPushCastIntoControlFunctionForHybridType(ctx, expr, tp)
 	var fc functionClass
 	switch tp.EvalType() {
 	case types.ETInt:
@@ -1985,3 +1986,92 @@ func WrapWithCastAsJSON(ctx sessionctx.Context, expr Expression) Expression {
 	}
 	return BuildCastFunction(ctx, expr, tp)
 }
+
+// TryPushCastIntoControlFunctionForHybridType try to push cast into control function for Hybrid Type.
+// If necessary, it will rebuild control function using changed args.
+// When a hybrid type is the output of a control function, the result may be as a numeric type to subsequent calculation
+// We should perform the `Cast` operation early to avoid using the wrong type for calculation
+// For example, the condition `if(1, e, 'a') = 1`, `if` function will output `e` and compare with `1`.
+// If the evaltype is ETString, it will get wrong result. So we can rewrite the condition to
+// `IfInt(1, cast(e as int), cast('a' as int)) = 1` to get the correct result.
+func TryPushCastIntoControlFunctionForHybridType(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression) {
+	sf, ok := expr.(*ScalarFunction)
+	if !ok {
+		return expr
+	}
+
+	var wrapCastFunc func(ctx sessionctx.Context, expr Expression) Expression
+	switch tp.EvalType() {
+	case types.ETInt:
+		wrapCastFunc = WrapWithCastAsInt
+	case types.ETReal:
+		wrapCastFunc = WrapWithCastAsReal
+	default:
+		return expr
+	}
+
+	isHybrid := func(ft *types.FieldType) bool {
+		// todo: compatible with mysql control function using bit type. issue 24725
+		return ft.Hybrid() && ft.Tp != mysql.TypeBit
+	}
+
+	args := sf.GetArgs()
+	switch sf.FuncName.L {
+	case ast.If:
+		if isHybrid(args[1].GetType()) || isHybrid(args[2].GetType()) {
+			args[1] = wrapCastFunc(ctx, args[1])
+			args[2] = wrapCastFunc(ctx, args[2])
+			f, err := funcs[ast.If].getFunction(ctx, args)
+			if err != nil {
+				return expr
+			}
+			sf.RetType, sf.Function = f.getRetTp(), f
+			return sf
+		}
+	case ast.Case:
+		hasHybrid := false
+		for i := 0; i < len(args)-1; i += 2 {
+			hasHybrid = hasHybrid || isHybrid(args[i+1].GetType())
+		}
+		if len(args)%2 == 1 {
+			hasHybrid = hasHybrid || isHybrid(args[len(args)-1].GetType())
+		}
+		if !hasHybrid {
+			return expr
+		}
+
+		for i := 0; i < len(args)-1; i += 2 {
+			args[i+1] = wrapCastFunc(ctx, args[i+1])
+		}
+		if len(args)%2 == 1 {
+			args[len(args)-1] = wrapCastFunc(ctx, args[len(args)-1])
+		}
+		f, err := funcs[ast.Case].getFunction(ctx, args)
+		if err != nil {
+			return expr
+		}
+		sf.RetType, sf.Function = f.getRetTp(), f
+		return sf
+	case ast.Elt:
+		hasHybrid := false
+		for i := 1; i < len(args); i++ {
+			hasHybrid = hasHybrid || isHybrid(args[i].GetType())
+		}
+		if !hasHybrid {
+			return expr
+		}
+
+		for i := 1; i < len(args); i++ {
+			args[i] = wrapCastFunc(ctx, args[i])
+		}
+		f, err := funcs[ast.Elt].getFunction(ctx, args)
+		if err != nil {
+			return expr
+		}
+		sf.RetType, sf.Function = f.getRetTp(), f
+		return sf
+	default:
+		return expr
+	}
+	return expr
+}

expression/integration_test.go

@@ -9364,6 +9364,79 @@ func (s *testIntegrationSuite) TestIssue29244(c *C) {
 	tk.MustQuery("select microsecond(a) from t;").Check(testkit.Rows("123500", "123500"))
 }
 
+func (s *testIntegrationSuite) TestControlFunctionWithEnumOrSet(c *C) {
+	defer s.cleanEnv(c)
+
+	// issue 23114
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists e;")
+	tk.MustExec("create table e(e enum('c', 'b', 'a'));")
+	tk.MustExec("insert into e values ('a'),('b'),('a'),('b');")
+	tk.MustQuery("select e from e where if(e>1, e, e);").Sort().Check(
+		testkit.Rows("a", "a", "b", "b"))
+	tk.MustQuery("select e from e where case e when 1 then e else e end;").Sort().Check(
+		testkit.Rows("a", "a", "b", "b"))
+	tk.MustQuery("select e from e where case 1 when e then e end;").Check(testkit.Rows())
+
+	tk.MustQuery("select if(e>1,e,e)='a' from e").Sort().Check(
+		testkit.Rows("0", "0", "1", "1"))
+	tk.MustQuery("select if(e>1,e,e)=1 from e").Sort().Check(
+		testkit.Rows("0", "0", "0", "0"))
+	// if and if
+	tk.MustQuery("select if(e>2,e,e) and if(e<=2,e,e) from e;").Sort().Check(
+		testkit.Rows("1", "1", "1", "1"))
+	tk.MustQuery("select if(e>2,e,e) and (if(e<3,0,e) or if(e>=2,0,e)) from e;").Sort().Check(
+		testkit.Rows("0", "0", "1", "1"))
+	tk.MustQuery("select * from e where if(e>2,e,e) and if(e<=2,e,e);").Sort().Check(
+		testkit.Rows("a", "a", "b", "b"))
+	tk.MustQuery("select * from e where if(e>2,e,e) and (if(e<3,0,e) or if(e>=2,0,e));").Sort().Check(
+		testkit.Rows("a", "a"))
+
+	// issue 24494
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(a int,b enum(\"b\",\"y\",\"1\"));")
+	tk.MustExec("insert into t values(0,\"y\"),(1,\"b\"),(null,null),(2,\"1\");")
+	tk.MustQuery("SELECT count(*) FROM t where if(a,b ,null);").Check(testkit.Rows("2"))
+
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(a int,b enum(\"b\"),c enum(\"c\"));")
+	tk.MustExec("insert into t values(1,1,1),(2,1,1),(1,1,1),(2,1,1);")
+	tk.MustQuery("select a from t where if(a=1,b,c)=\"b\";").Check(testkit.Rows("1", "1"))
+	tk.MustQuery("select a from t where if(a=1,b,c)=\"c\";").Check(testkit.Rows("2", "2"))
+	tk.MustQuery("select a from t where if(a=1,b,c)=1;").Sort().Check(testkit.Rows("1", "1", "2", "2"))
+	tk.MustQuery("select a from t where if(a=1,b,c);").Sort().Check(testkit.Rows("1", "1", "2", "2"))
+
+	tk.MustExec("drop table if exists e;")
+	tk.MustExec("create table e(e enum('c', 'b', 'a'));")
+	tk.MustExec("insert into e values(3)")
+	tk.MustQuery("select elt(1,e) = 'a' from e").Check(testkit.Rows("1"))
+	tk.MustQuery("select elt(1,e) = 3 from e").Check(testkit.Rows("1"))
+	tk.MustQuery("select e from e where elt(1,e)").Check(testkit.Rows("a"))
+
+	// test set type
+	tk.MustExec("drop table if exists s;")
+	tk.MustExec("create table s(s set('c', 'b', 'a'));")
+	tk.MustExec("insert into s values ('a'),('b'),('a'),('b');")
+	tk.MustQuery("select s from s where if(s>1, s, s);").Sort().Check(
+		testkit.Rows("a", "a", "b", "b"))
+	tk.MustQuery("select s from s where case s when 1 then s else s end;").Sort().Check(
+		testkit.Rows("a", "a", "b", "b"))
+	tk.MustQuery("select s from s where case 1 when s then s end;").Check(testkit.Rows())
+
+	tk.MustQuery("select if(s>1,s,s)='a' from s").Sort().Check(
+		testkit.Rows("0", "0", "1", "1"))
+	tk.MustQuery("select if(s>1,s,s)=4 from s").Sort().Check(
+		testkit.Rows("0", "0", "1", "1"))
+
+	tk.MustExec("drop table if exists s;")
+	tk.MustExec("create table s(s set('c', 'b', 'a'));")
+	tk.MustExec("insert into s values('a')")
+	tk.MustQuery("select elt(1,s) = 'a' from s").Check(testkit.Rows("1"))
+	tk.MustQuery("select elt(1,s) = 4 from s").Check(testkit.Rows("1"))
+	tk.MustQuery("select s from s where elt(1,s)").Check(testkit.Rows("a"))
+}
+
 func (s *testIntegrationSuite) TestIssue29513(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")

planner/core/logical_plan_builder.go

@@ -977,6 +977,19 @@ func (b *PlanBuilder) buildSelection(ctx context.Context, p LogicalPlan, where a
 	if len(cnfExpres) == 0 {
 		return p, nil
 	}
+	// check expr field types.
+	for i, expr := range cnfExpres {
+		if expr.GetType().EvalType() == types.ETString {
+			tp := &types.FieldType{
+				Tp:      mysql.TypeDouble,
+				Flag:    expr.GetType().Flag,
+				Flen:    mysql.MaxRealWidth,
+				Decimal: types.UnspecifiedLength,
+			}
+			types.SetBinChsClnFlag(tp)
+			cnfExpres[i] = expression.TryPushCastIntoControlFunctionForHybridType(b.ctx, expr, tp)
+		}
+	}
 	selection.Conditions = cnfExpres
 	selection.SetChildren(p)
 	return selection, nil