From 1ff5fc8a23f9438e1575fad217ff0389f45bebcd Mon Sep 17 00:00:00 2001
From: ti-srebot <66930949+ti-srebot@users.noreply.github.com>
Date: Thu, 19 Nov 2020 15:25:27 +0800
Subject: [PATCH] cherry pick #21127 to release-4.0 (#21135)

---
 server/util.go      | 14 +++++++++++++-
 server/util_test.go |  2 +-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/server/util.go b/server/util.go
index 7150229ebc0fc..88bcdc35086e2 100644
--- a/server/util.go
+++ b/server/util.go
@@ -208,12 +208,24 @@ func dumpBinaryDateTime(data []byte, t types.Time) []byte {
 	switch t.Type() {
 	case mysql.TypeTimestamp, mysql.TypeDatetime:
 		if t.IsZero() {
+			// All zero.
 			data = append(data, 0)
-		} else {
+		} else if t.Microsecond() != 0 {
+			// Has micro seconds.
 			data = append(data, 11)
 			data = dumpUint16(data, uint16(year))
 			data = append(data, byte(mon), byte(day), byte(t.Hour()), byte(t.Minute()), byte(t.Second()))
 			data = dumpUint32(data, uint32(t.Microsecond()))
+		} else if t.Hour() != 0 || t.Minute() != 0 || t.Second() != 0 {
+			// Has HH:MM:SS
+			data = append(data, 7)
+			data = dumpUint16(data, uint16(year))
+			data = append(data, byte(mon), byte(day), byte(t.Hour()), byte(t.Minute()), byte(t.Second()))
+		} else {
+			// Only YY:MM:DD
+			data = append(data, 4)
+			data = dumpUint16(data, uint16(year))
+			data = append(data, byte(mon), byte(day))
 		}
 	case mysql.TypeDate:
 		if t.IsZero() {
diff --git a/server/util_test.go b/server/util_test.go
index d3148fc187693..a11641c33ffae 100644
--- a/server/util_test.go
+++ b/server/util_test.go
@@ -84,7 +84,7 @@ func (s *testUtilSuite) TestDumpBinaryTime(c *C) {
 	c.Assert(err, IsNil)
 	d = dumpBinaryDateTime(nil, t)
 	// 201 & 7 composed to uint16 1993 (litter-endian)
-	c.Assert(d, DeepEquals, []byte{11, 201, 7, 7, 13, 1, 1, 1, 0, 0, 0, 0})
+	c.Assert(d, DeepEquals, []byte{7, 201, 7, 7, 13, 1, 1, 1})
 
 	t, err = types.ParseDate(nil, "0000-00-00")
 	c.Assert(err, IsNil)