Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

mysql> create table t ( b timestamp(3) NOT NULL DEFAULT '1970-01-01 08:00:01.000' COMMENT '');
Query OK, 0 rows affected (0.08 sec)

mysql> show create table t;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------+
| t | CREATE TABLE t (
b timestamp(3) NOT NULL DEFAULT '1970-01-01 08:00:01.000'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select column_default from information_schema.columns where TABLE_NAME='t';
+-------------------------+
| column_default |
+-------------------------+
| 1970-01-01 00:00:01.000 |
+-------------------------+
1 row in set (0.03 sec)

2. What did you expect to see? (Required)

In mysql:

mysql> create table t ( b timestamp(3) NOT NULL DEFAULT '1970-01-01 08:00:01.000' COMMENT '');
Query OK, 0 rows affected (0.00 sec)

mysql> show create table t;
+-------+-------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-------------------------------------------------------------------------------------------------------------------------+
| t | CREATE TABLE t (
b timestamp(3) NOT NULL DEFAULT '1970-01-01 08:00:01.000'
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select column_default from information_schema.columns where TABLE_NAME='t';
+-------------------------+
| column_default |
+-------------------------+
| 1970-01-01 08:00:01.000 |
+-------------------------+
1 row in set (0.01 sec)

3. What did you see instead (Required)

show create table's result and information_schema.columns's result are inconsistent!

4. What is your TiDB version? (Required)

mysql> mysql> select version();
+-----------------------------------------+
| version() |
+-----------------------------------------+
| 5.7.25-TiDB-v5.4.0-alpha-178-g02a8f0453 |
+-----------------------------------------+
1 row in set (0.00 sec)