replication: return string when datetime's day or month is 00

MySQL supports 0 for day/month when this is an unknown value

This cannot be encoded into a time.Time, where time.Date normalizes these 0s
(so 2000-00-00 would become 1999-11-30)

Pass these values through in their raw string form instead

Author: serprex

replication/row_event.go

@@ -1316,7 +1316,7 @@ func (e *RowsEvent) decodeValue(data []byte, tp byte, meta uint16, isPartial boo
 		n = 4
 		t := binary.LittleEndian.Uint32(data)
 		if t == 0 {
-			v = formatZeroTime(0, 0)
+			v = "0000-00-00 00:00:00"
 		} else {
 			v = e.parseFracTime(fracTime{
 				Time:                    time.Unix(int64(t), 0),
@@ -1331,23 +1331,34 @@ func (e *RowsEvent) decodeValue(data []byte, tp byte, meta uint16, isPartial boo
 		n = 8
 		i64 := binary.LittleEndian.Uint64(data)
 		if i64 == 0 {
-			v = formatZeroTime(0, 0)
+			v = "0000-00-00 00:00:00"
 		} else {
 			d := i64 / 1000000
 			t := i64 % 1000000
-			v = e.parseFracTime(fracTime{
-				Time: time.Date(
-					int(d/10000),
-					time.Month((d%10000)/100),
-					int(d%100),
-					int(t/10000),
-					int((t%10000)/100),
-					int(t%100),
-					0,
-					time.UTC,
-				),
-				Dec: 0,
-			})
+			years := int(d / 10000)
+			months := (d % 10000) / 100
+			days := int(d % 100)
+			hours := int(t / 10000)
+			minutes := int((t % 10000) / 100)
+			seconds := int(t % 100)
+			if months == 0 || days == 0 {
+				v = fmt.Sprintf("%04d-%02d-%02d %02d:%02d:%02d",
+					years, months, days, hours, minutes, seconds)
+			} else {
+				v = e.parseFracTime(fracTime{
+					Time: time.Date(
+						int(d/10000),
+						time.Month((d%10000)/100),
+						int(d%100),
+						int(t/10000),
+						int((t%10000)/100),
+						int(t%100),
+						0,
+						time.UTC,
+					),
+					Dec: 0,
+				})
+			}
 		}
 	case mysql.MYSQL_TYPE_DATETIME2:
 		v, n, err = decodeDatetime2(data, meta)
@@ -1725,7 +1736,7 @@ func decodeDatetime2(data []byte, dec uint16) (interface{}, int, error) {
 	// minute = 0 = 0b000000
 	// second = 0 = 0b000000
 	// integer value = 0b1100100000010110000100000000000000000 = 107420450816
-	if intPart < 107420450816 {
+	if intPart < 107420450816 || month == 0 || day == 0 {
 		return formatBeforeUnixZeroTime(year, month, day, hour, minute, second, int(frac), int(dec)), n, nil
 	}
 

replication/row_event_test.go

@@ -675,6 +675,8 @@ func TestDecodeDatetime2(t *testing.T) {
 	}{
 		{[]byte("\xfe\xf3\xff\x7e\xfb"), 0, true, "9999-12-31 23:59:59"},
 		{[]byte("\x99\x9a\xb8\xf7\xaa"), 0, true, "2016-10-28 15:30:42"},
+		{[]byte("\x99\x98\x38\xf7\xaa"), 0, false, "2016-00-28 15:30:42"},
+		{[]byte("\x99\x9a\x80\xf7\xaa"), 0, false, "2016-10-00 15:30:42"},
 		{[]byte("\x99\x02\xc2\x00\x00"), 0, true, "1970-01-01 00:00:00"},
 		{[]byte("\x80\x00\x00\x00\x00"), 0, false, "0000-00-00 00:00:00"},
 		{[]byte("\x80\x00\x02\xf1\x05"), 0, false, "0000-00-01 15:04:05"},