cherry pick pingcap#37820 to release-5.3

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

types/time.go

@@ -556,9 +556,17 @@ func GetFsp(s string) int8 {
 
 // GetFracIndex finds the last '.' for get fracStr, index = -1 means fracStr not found.
 // but for format like '2019.01.01 00:00:00', the index should be -1.
+// It will not be affected by the time zone suffix. For format like '2020-01-01 12:00:00.123456+05:00', the index should be 19.
 func GetFracIndex(s string) (index int) {
+	tzIndex, _, _, _, _ := GetTimezone(s)
+	var end int
+	if tzIndex != -1 {
+		end = tzIndex - 1
+	} else {
+		end = len(s) - 1
+	}
 	index = -1
-	for i := len(s) - 1; i >= 0; i-- {
+	for i := end; i >= 0; i-- {
 		if unicode.IsPunct(rune(s[i])) {
 			if s[i] == '.' {
 				index = i

types/time_test.go

@@ -111,6 +111,9 @@ func TestDateTime(t *testing.T) {
 		{"2020-05-28 23:59:59T T00:00:00", "2020-05-28 23:59:59"},
 		{"2020-10-22 10:31-10:12", "2020-10-22 10:31:10"},
 		{"2018.01.01 01:00:00", "2018-01-01 01:00:00"},
+
+		// For issue 35291
+		{"2020-01-01 12:00:00.123456+05:00", "2020-01-01 07:00:00.123456"},
 	}
 
 	for _, test := range table {