概述

简单写了一个存储过程对mysql数据库中的表进行批量碎片清理，建议在业务空闲时间段进行。

思路

核心是利用mysql系统表和“optimize table 表名”命令，对mysql数据表进行空间的释放。由于delete和drop table都不会释放表空间（truncate 命令会释放表空间），所以需要利用optimize 命令进行释放。

这个存储过程目的是给一个库的所有表来整理碎片的。一个表随着插入很频繁，或者一直更新不停的，就会积累好多碎片。如果及时整理一下，查询效率会高出好多。

存储过程

整理如下：

DELIMITER $$DROP PROCEDURE IF EXISTS `mysql`.`sp_optimize_tables`$$CREATE PROCEDURE `mysql`.`sp_optimize_tables`( IN db_name varchar(255))BEGIN -- To optimize all the tables in exact database. declare cnt int default 0; declare i int default 0; select count(*) as total from information_schema.tables where table_schema = db_name into cnt; while i < cnt do -- Get the table's exact name. set @stmt = concat('select table_name from information_schema.tables where table_schema = ''',db_name,''' order by table_name asc limit ',i,',1 into @tb_name'); prepare s1 from @stmt; execute s1; drop prepare s1; set @stmt = ''; set @stmt = concat('optimize table ',db_name,'.',@tb_name); prepare s1 from @stmt; execute s1; drop prepare s1; set @stmt = ''; set i = i + 1; end while; -- Refresh tables. flush tables;END$$DELIMITER ;

因为optimize有一些限定条件，所以也可以改成alter ... engine=innodb;这种方式。

DELIMITER $$DROP PROCEDURE IF EXISTS `mysql`.`sp_optimize_tables2`$$CREATE PROCEDURE `mysql`.`sp_optimize_tables2`( IN db_name varchar(255))BEGIN -- To optimize all the tables in exact database. declare cnt int default 0; declare i int default 0; select count(*) as total from information_schema.tables where table_schema = db_name into cnt; while i < cnt do -- Get the table's exact name. set @stmt = concat('select table_name from information_schema.tables where table_schema = ''',db_name,''' order by table_name asc limit ',i,',1 into @tb_name'); prepare s1 from @stmt; execute s1; drop prepare s1; set @stmt = ''; set @stmt = concat('alter table ',db_name,'.',@tb_name,' engine=innodb'); prepare s1 from @stmt; execute s1; drop prepare s1; set @stmt = ''; set i = i + 1; end while; -- Refresh tables. flush tables;END$$DELIMITER ;

调用示例：

mysql> use mysqlmysql> call sp_optimize_tables('database_name');

因为我这表都是innodb，所以采用alter table XX engine=innodb方式。

mysql> use mysqlmysql> call sp_optimize_tables2('database_name');

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