MySQL分区表实现按月份归类

建表

一般的表（innodb）创建后只有一个 idb 文件:

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									create table normal_table(id int primary key, no int)

查看数据库文件：

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									normal_table.ibd

创建按月份分区的分区表，注意！除了常规主键外，月份字段（用来分区的字段）也必须是主键：

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									create table partition_table(id int AUTO_INCREMENT, create_date date, name varchar(10), 

									primary key(id, create_date)) ENGINE=INNODB DEFAULT CHARSET=utf8 

									partition by range(month(create_date))(

									partition quarter1 values less than(4),

									partition quarter2 values less than(7),

									partition quarter3 values less than(10),

									partition quarter4 values less than(13)

									);

查看数据库文件：

partition_table# p#quarter1.ibd
partition_table# p#quarter2.ibd
partition_table# p#quarter3.ibd
partition_table# p#quarter4.ibd

插入

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									insert into partition_table(create_date, name) values("2021-01-25", "tom1");

									insert into partition_table(create_date, name) values("2021-02-25", "tom2");

									insert into partition_table(create_date, name) values("2021-03-25", "tom3");

									insert into partition_table(create_date, name) values("2021-04-25", "tom4");

									insert into partition_table(create_date, name) values("2021-05-25", "tom5");

									insert into partition_table(create_date, name) values("2021-06-25", "tom6");

									insert into partition_table(create_date, name) values("2021-07-25", "tom7");

									insert into partition_table(create_date, name) values("2021-08-25", "tom8");

									insert into partition_table(create_date, name) values("2021-09-25", "tom9");

									insert into partition_table(create_date, name) values("2021-10-25", "tom10");

									insert into partition_table(create_date, name) values("2021-11-25", "tom11");

									insert into partition_table(create_date, name) values("2021-12-25", "tom12");

查询

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									select count(*) from partition_table;

									> 12

									查询第二个分区（第二季度）的数据：

									select * from partition_table PARTITION(quarter2);

									4 2021-04-25 tom4

									5 2021-05-25 tom5

									6 2021-06-25 tom6

删除

当删除表时，该表的所有分区文件都会被删除

补充：Mysql自动按月表分区

核心的两个存储过程：

auto_create_partition为创建表分区，调用后为该表创建到下月结束的表分区。
auto_del_partition为删除表分区，方便历史数据空间回收。

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									DELIMITER $$

									DROP PROCEDURE IF EXISTS auto_create_partition$$

									CREATE PROCEDURE `auto_create_partition`(IN `table_name` varchar(64))

									BEGIN

									   SET @next_month:=CONCAT(date_format(date_add(now(),interval 2 month),'%Y%m'),'01');

									   SET @SQL = CONCAT( 'ALTER TABLE `', table_name, '`',

									     ' ADD PARTITION (PARTITION p', @next_month, " VALUES LESS THAN (TO_DAYS(",

									       @next_month ,")) );" );

									   PREPARE STMT FROM @SQL;

									   EXECUTE STMT;

									   DEALLOCATE PREPARE STMT;

									END$$

									DROP PROCEDURE IF EXISTS auto_del_partition$$

									CREATE PROCEDURE `auto_del_partition`(IN `table_name` varchar(64),IN `reserved_month` int)

									BEGIN

									 DECLARE v_finished INTEGER DEFAULT 0;

									 DECLARE v_part_name varchar(100) DEFAULT "";

									 DECLARE part_cursor CURSOR FOR

									  select partition_name from information_schema.partitions where table_schema = schema()

									   and table_name=@table_name and partition_description < TO_DAYS(CONCAT(date_format(date_sub(now(),interval reserved_month month),'%Y%m'),'01'));

									 DECLARE continue handler FOR

									  NOT FOUND SET v_finished = TRUE;

									 OPEN part_cursor;

									read_loop: LOOP

									 FETCH part_cursor INTO v_part_name;

									 if v_finished = 1 then

									  leave read_loop;

									 end if;

									 SET @SQL = CONCAT( 'ALTER TABLE `', table_name, '` DROP PARTITION ', v_part_name, ";" );

									 PREPARE STMT FROM @SQL;

									 EXECUTE STMT;

									 DEALLOCATE PREPARE STMT;

									 END LOOP;

									 CLOSE part_cursor;

									END$$

									DELIMITER ;

下面是示例

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									-- 假设有个表叫records,设置分区条件为按end_time按月分区

									DROP TABLE IF EXISTS `records`;

									CREATE TABLE `records` (

									  `id` int(11) NOT NULL AUTO_INCREMENT,

									  `start_time` datetime NOT NULL,

									  `end_time` datetime NOT NULL,

									  `memo` varchar(128) CHARACTER SET utf8mb4 NOT NULL,

									  PRIMARY KEY (`id`,`end_time`)

									) 

									PARTITION BY RANGE (TO_DAYS(end_time))(

									 PARTITION p20200801 VALUES LESS THAN ( TO_DAYS('20200801'))

									);

									DROP EVENT IF EXISTS `records_auto_partition`;

									-- 创建一个Event,每月执行一次，同时最多保存6个月的数据

									DELIMITER $$

									CREATE EVENT `records_auto_partition`

									ON SCHEDULE EVERY 1 MONTH ON COMPLETION PRESERVE

									ENABLE

									DO

									BEGIN

									call auto_create_partition('records');

									call auto_del_partition('records',6);

									END$$

									DELIMITER ;

几点注意事项：

对于Mysql 5.1以上版本来说，表分区的索引字段必须是主键
存储过程中，DECLARE 必须紧跟着BEGIN，否则会报看不懂的错误
游标的DECLARE需要在定义声明之后，否则会报错
如果是自己安装的Mysql，有可能Event功能是未开启的，在创建Event时会提示错误；修改my.cnf,在 [mysqld] 下添加event_scheduler=1后重启即可。

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原文链接：https://blog.csdn.net/qq_40310224/article/details/119921331