喀秋莎的技术博客 | 快乐每一天夏虫不可以语冰

EXPLAIN key_length

2016-08-18

varcahr(m) key_len=m*3+2

关于NULL to NOT NULL

2016-08-10

The NULL value means “no data.”

The NULL value can be surprising until you get used to it. Conceptually, NULL means “a missing unknown value” and it is treated somewhat differently from other values.

Redis INFO输出文本后的编码问题

2016-08-10

我们在监控Redis的时候依赖服务的当前的运行状态，Redis相对简易，需要我们自己到INFO里面去抓数据

自增主键同步差异后的故障切换，自增主键冲突

2016-07-28

接上文Replace into 带来的主从自增主键差异后，故障切换后的数据写入冲突

Replace into 带来的主从自增主键差异

2016-07-22

环境

CREATE TABLE `t` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `age` int(11) DEFAULT NULL,
  `msg` varchar(10) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `uniq_age` (`age`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into t (age, msg) values (1,'aaa'),(2,'bbb'),(3,'ccc');
select * from t;
+----+------+------+
| id | age  | msg  |
+----+------+------+
|  1 |    1 | aaa  |
|  2 |    2 | bbb  |
|  3 |    3 | ccc  |
+----+------+------+
3 rows in set (0.01 sec)