INNODB 不支持 mysql> OPTIMIZE TABLE t;
+--------+----------+----------+-------------------------------------------------------------------+
| Table | Op | Msg_type | Msg_text |
+--------+----------+----------+-------------------------------------------------------------------+
| test.t | optimize | note | Table does not support optimize, doing recreate + analyze instead | //INNODB
| test.t | optimize | status | OK |
+--------+----------+----------+-------------------------------------------------------------------+
2 rows in set (0.24 sec)
mysql> show create table t;
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
| t | CREATE TABLE `t` (
`a` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`a`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8 |
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.18 sec)
使 OPTIMIZE table 对 innodb 支持
mysqld --datadir=/data --basedir=/usr/local/mysql56 --user=mysql --gdb --skip-new
mysql> OPTIMIZE TABLE t;
Query OK, 0 rows affected (0.27 sec)
Records: 0 Duplicates: 0 Warnings: 0
原理：映射为 alter table
By default, OPTIMIZE TABLE does not work for tables created using any other storage engine and returns a result indicating this lack of support. You can make OPTIMIZTABLE work for other storage engines by starting mysqld with the --skip-new option. In this case, OPTIMIZE TABLE is just mapped to ALTER TABLE.
OPTIMIZE TABLE continues to use ALGORITHM=COPY under the following conditions: When the old_alter_table system variable is turned ON. set old_alter_table=on; //alter table 修改表采用 algorithm=copy 方式 When the mysqld --skip-new option is enabled.
google: Everytime you do optimize MySQL, by using mysqlcheck -A -o or using ./mysql_optimize from here.
You may see the output Table does not support optimize, doing recreate + analyze instead. It is because the table that you are using is InnoDB. You can optimize the InnoDB tables by using this. ALTER TABLE table.name ENGINE='InnoDB'; This will create a copy of the original table, and drop the original table, and replace to the original place. Although this is safe, but I suggest you do backup and test first before doing this.
mysql> ALTER TABLE t ENGINE='InnoDB';
Query OK, 0 rows affected (0.29 sec)
Records: 0 Duplicates: 0 Warnings: 0 mysql> select * from t;
+---+
| a |
+---+
| 7 |
+---+
1 row in set (0.01 sec)
innodb的数据库不支持optimize，可以用ALTER TABLE table.name ENGINE='InnoDB';
该方法会对旧表以复制的方式新建一个新表，然后删除旧表。虽然这个过程是安全的,
但是在进行操作时还是先进行备份为好
MyISAM:正常
mysql> show create table t;
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
| t | CREATE TABLE `t` (
`a` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`a`)
) ENGINE=MyISAM AUTO_INCREMENT=8 DEFAULT CHARSET=utf8 |
+-------+-------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec) mysql> OPTIMIZE TABLE t;
+--------+----------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------+----------+----------+----------+
| test.t | optimize | status | OK |
+--------+----------+----------+----------+
1 row in set (0.00 sec)