expression: resize the result for IfXXSig (pingcap#37417) (pingcap#37431

)

close pingcap#37414

expression/generator/control_vec.go

@@ -230,6 +230,7 @@ var builtinIfNullVec = template.Must(template.New("builtinIfNullVec").Parse(`
 func (b *builtinIfNull{{ .TypeName }}Sig) fallbackEval{{ .TypeName }}(input *chunk.Chunk, result *chunk.Column) error {
 	n := input.NumRows()
 	{{- if .Fixed }}
+	result.Resize{{ .TypeNameInColumn }}(n, false)
 	x := result.{{ .TypeNameInColumn }}s()
 	for i := 0; i < n; i++ {
 		res, isNull, err := b.eval{{ .TypeName }}(input.GetRow(i))
@@ -345,6 +346,7 @@ var builtinIfVec = template.Must(template.New("builtinIfVec").Parse(`
 func (b *builtinIf{{ .TypeName }}Sig) fallbackEval{{ .TypeName }}(input *chunk.Chunk, result *chunk.Column) error {
 	n := input.NumRows()
 	{{- if .Fixed }}
+	result.Resize{{ .TypeNameInColumn }}(n, false)
 	x := result.{{ .TypeNameInColumn }}s()
 	for i := 0; i < n; i++ {
 		res, isNull, err := b.eval{{ .TypeName }}(input.GetRow(i))

expression/integration_test.go

@@ -6281,6 +6281,20 @@ func TestRedundantColumnResolve(t *testing.T) {
 	tk.MustQuery("select t1.a, t2.a from t1 natural join t2").Check(testkit.Rows("1 1"))
 }
 
+func TestIssue37414(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 foo")
+	tk.MustExec("drop table if exists bar")
+	tk.MustExec("create table foo(a decimal(65,0));")
+	tk.MustExec("create table bar(a decimal(65,0), b decimal(65,0));")
+	tk.MustExec("insert into bar values(0,0),(1,1),(2,2);")
+	tk.MustExec("insert into foo select if(b>0, if(a/b>1, 1, 2), null) from bar;")
+}
+
 func TestControlFunctionWithEnumOrSet(t *testing.T) {
 	// issue 23114
 	store, clean := testkit.CreateMockStore(t)