column type change will write the invalid timestamp value

[AilinKid]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

Only can reproduce it Real TiKV Cluster

CREATE TABLE `t` (`a` DATE NULL DEFAULT '8497-01-06');
alter table t modify column a  TIMESTAMP NULL DEFAULT '2021-04-28 03:35:11' FIRST"; // hang it
insert into `t` set  `a` = '3977-02-22'   //  在 write only 及之后状态写下去

Maybe the root cause is

mysql> select cast('3977-02-22' as datetime);
+--------------------------------+
| cast('3977-02-22' as datetime) |
+--------------------------------+
| 3977-02-22 00:00:00            |
+--------------------------------+
1 row in set (0.00 sec)

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

DML failed with incorrect value

3. What did you see instead (Required)

DML succeed and the latter select fail with incorrect value

4. What is your TiDB version? (Required)

master

[zimulala]

We can check why the normal insert will return an error, but the WriteOnly insert is normal.

tidb> CREATE TABLE `t` (`a` DATE NULL DEFAULT '8497-01-06', `b` TIMESTAMP NULL DEFAULT '2021-04-28 03:35:11');
Query OK, 0 rows affected (0.01 sec)
tidb> insert into `t` set  `b` = '3977-02-22' ;
ERROR 1292 (22007): Incorrect timestamp value: '3977-02-22' for column 'b' at row 1

[AilinKid]

quick similar like #25560

mysql> select timestamp(cast("3977-02-22" as date));
+---------------------------------------+
| timestamp(cast("3977-02-22" as date)) |
+---------------------------------------+
| 3977-02-22 00:00:00                   |
+---------------------------------------+
1 row in set (0.01 sec)

1: when in pure insert statement, cast "3977-02-22" to timestamp will errors (incorrest timestamp value)

2: when in mid-state insert statement, cast "3977-02-22" to date datum first, then the changing col cast date datum to timestamp, which is ok here.

[ti-srebot]

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