告警升级公告
auto_increment，即支持一个全局的自增字段，auto_increment 可以保证该表某个字段全局唯一，但不保证单调递增，具体使用方法如下：mysql> create table auto_inc (a int,b int,c int auto_increment,d int,key auto(c),primary key p(a,d)) shardkey=d;Query OK, 0 rows affected (0.12 sec)
mysql> insert into shard.auto_inc ( a,b,d,c) values(1,2,3,0),(1,2,4,0);Query OK, 2 rows affected (0.05 sec)Records: 2 Duplicates: 0 Warnings: 0mysql> select * from shard.auto_inc;+---+------+---+---+| a | b | c | d |+---+------+---+---+| 1 | 2 | 2 | 4 || 1 | 2 | 1 | 3 |+---+------+---+---+2 rows in set (0.03 sec)
mysql> insert into shard.auto_inc ( a,b,d,c) values(11,12,13,0),(21,22,23,0);Query OK, 2 rows affected (0.03 sec)mysql> select * from shard.auto_inc;+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+| a | b | c | d |+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+| 21 | 22 | 2002 | 23 || 1 | 2 | 2 | 4 || 1 | 2 | 1 | 3 || 11 | 12 | 2001 | 13 |+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+‐‐‐‐‐‐+4 rows in set (0.01 sec)
alter table auto_inc auto_increment=100
select last_insert_id()获取最近一个自增值：mysql> insert into auto_inc ( a,b,d,c) values(1,2,3,0),(1,2,4,0);Query OK, 2 rows affected (0.73 sec)mysql> select * from auto_inc;+---+------+------+---+| a | b | c | d |+---+------+------+---+| 1 | 2 | 4001 | 3 || 1 | 2 | 4002 | 4 |+---+------+------+---+2 rows in set (0.00 sec)mysql> select last_insert_id();+------------------+| last_insert_id() |+------------------+| 4001 |+------------------+1 row in set (0.00 sec)
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