AUTO_INCREMENT behaviour different between MySQL and TiDB

[tiancaiamao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

set @@auto_increment_increment = 5;
set @@auto_increment_offset = 10;
create table io (a int key auto_increment);
insert into io values (null),(null),(null);

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

mysql> select * from io;
+----+
| a  |
+----+
|  4 |
|  9 |
| 10 |
+----+
3 rows in set (0.00 sec)

3. What did you see instead (Required)

mysql> select * from io;
+----+
| a  |
+----+
| 10 |
| 15 |
| 20 |
+----+
3 rows in set (0.00 sec)

4. What is your TiDB version? (Required)

master b9029f1

[tiancaiamao]

Ref #38442

[tiancaiamao]

tidb/executor/insert_test.go

Line 1137 in e415cfa

// This issue is a flaw of the implementation of MySQL and it doesn't exist in TiDB.

It's a flaw of the implementation of MySQL, so TiDB doesn't follow this behaviour.