引用MySQL官方文档中的一段话:MERGE存储引擎,也被认识为MRG_MyISAM引擎,是一个相同的可以被当作一个来用的MyISAM表的集合.相同简介:引用mysql官方文档中的一段话:merge存储引擎,也被认识为mrg_myisam引擎,是一个相同的可以被当作一个来用的myisam表的集合."相同"意味着所有表同样的列和索引信息.你不能合并列被以不同顺序列于其中的表,没有恰好同样列的表,或有不同顺序索引的表.而且,任何或者所有的表可以用myisampack来压缩.
例子:mysql> show engines;+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+| Engine | Support | Comment | Transactions | XA | Savepoints |+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO || MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO || MyISAM | YES | MyISAM storage engine | NO | NO | NO || BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO || CSV | YES | CSV storage engine | NO | NO | NO || PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO || ARCHIVE | YES | Archive storage engine | NO | NO | NO || FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL || InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+9 rows in set (0.00 sec) mysql> create table test1 (id int not null auto_increment,name varchar(10) default null ,primary key (id)) engine=myisam auto_increment=1;Query OK, 0 rows affected (0.01 sec) mysql> create table test2 (id int not null auto_increment,name varchar(10) default null ,primary key (id)) engine=myisam auto_increment=1;Query OK, 0 rows affected (0.00 sec) mysql> INSERT INTO `test1` (`name`) VALUES('beijing1');Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO `test2` (`name`) VALUES('beijing2');Query OK, 1 row affected (0.00 sec) mysql> create table test (id int not null auto_increment,name varchar(10) default null ,index(id)) engine=mrg_myisam union=(test1,test2) insert_method=last auto_increment=1;Query OK, 0 rows affected (0.03 sec) mysql> select id,name from test;+----+----------+| id | name |+----+----------+| 1 | beijing1 || 1 | beijing2 |+----+----------+2 rows in set (0.00 sec) mysql> INSERT INTO `test` (`name`) VALUES('beijing3');Query OK, 1 row affected (0.00 sec) mysql> select id,name from test;+----+----------+| id | name |+----+----------+| 1 | beijing1 || 1 | beijing2 || 2 | beijing3 |+----+----------+3 rows in set (0.00 sec)