1．背景原因
当前MySQL不支持在添加和删除分区时，使用IF NOT EXISTS和IF EXISTS。所以在执行调度任务时，直接通过ADD PARTITION和DROP PARTITION不可避免会报错。本文通过创建存储过程来添加和删除分区，可以避免在分区存在时添加分区报错，或者分区不存在时删除分区报错的问题。
本文介绍的是关于LIST分区的添加和删除。
2．前提准备
创建List分区表
- DROP TABLE IF EXISTS `list_part_table` ;
- CREATE TABLE IF NOT EXISTS `list_part_table` (
- `id` bigint(32) NOT NULL COMMENT '主键',
- `request_time` datetime(0) NOT NULL COMMENT '请求时间',
- `response_time` datetime(0) NOT NULL COMMENT '响应时间',
- `time_used` int(11) NOT NULL COMMENT '耗时(ms)',
- `create_by` varchar(48) DEFAULT NULL COMMENT '创建人',
- `update_by` varchar(48) DEFAULT NULL COMMENT '修改人',
- `create_time` datetime(0) NOT NULL DEFAULT CURRENT_TIMESTAMP(0) COMMENT '创建时间',
- `update_time` datetime(0) NULL DEFAULT CURRENT_TIMESTAMP(0) ON UPDATE CURRENT_TIMESTAMP(0) COMMENT '更新时间',
- PRIMARY KEY (`id`, `request_time`) USING BTREE
- ) PARTITION BY list(TO_DAYS(request_time)) (
- PARTITION p0 VALUES IN (0)
- ) ;
查看表中的分区信息
- select * from information_schema.partitions where table_name like 'list_part_table%' ;
3．添加和删除分区语句
（1）添加分区
- alter table list_part_table add partition(partition p202001 values in (202001));
- alter table list_part_table add partition(partition p20201201 values in (20201201));
查看表的分区信息
- select * from information_schema.partitions where table_name like 'list_part_table%' ;
（2）删除分区
- alter table list_part_table drop partition p202001,p20201201 ;
查看表的分区信息
- select * from information_schema.partitions where table_name like 'list_part_table%' ;
说明：当上面的添加分区和删除分区语句执行多次时，就会报错。
4．通过存储过程添加LIST分区
（1）添加分区的存储过程
- DROP PROCEDURE IF EXISTS create_list_partition ;
- DELIMITER $$
- CREATE PROCEDURE IF NOT EXISTS create_list_partition (par_value bigint, tb_schema varchar(128),tb_name varchar(128))
- BEGIN
-
- DECLARE par_name varchar(32);
- DECLARE par_value_str varchar(32);
- DECLARE par_exist int(1);
- DECLARE _err int(1);
- DECLARE CONTINUE HANDLER FOR SQLEXCEPTION, SQLWARNING, NOT FOUND SET _err = 1;
- START TRANSACTION;
- SET par_value_str = CONCAT('', par_value);
- SET par_name = CONCAT('p', par_value);
- SELECT COUNT(1) INTO par_exist FROM information_schema.PARTITIONS WHERE TABLE_SCHEMA = tb_schema AND TABLE_NAME = tb_name AND PARTITION_NAME = par_name;
- IF (par_exist = 0) THEN
-
- SET @alter_sql = CONCAT('alter table ', tb_name, ' add PARTITION (PARTITION ', par_name, ' VALUES IN (', par_value_str, '))');
- PREPARE stmt1 FROM @alter_sql;
- EXECUTE stmt1;
- END IF;
- COMMIT;
- END
- $$
（2）调用存储过程添加分区
添加分区
- CALL create_list_partition(202201, 'test', 'list_part_table');
- CALL create_list_partition(202202, 'test', 'list_part_table');
- CALL create_list_partition(20230912, 'test', 'list_part_table');
- CALL create_list_partition(20230913, 'test', 'list_part_table');
查看表的分区信息
- select * from information_schema.partitions where table_name like 'list_part_table%' ;
5．通过存储过程删除LIST分区
（1）删除分区的存储过程
- DROP PROCEDURE IF EXISTS drop_list_partition ;
- DELIMITER $$
- CREATE PROCEDURE IF NOT EXISTS drop_list_partition (part_value bigint, tb_schema varchar(128), tb_name varchar(128))
- BEGIN
-
- DECLARE str_day varchar(64);
- DECLARE _err int(1);
- DECLARE done int DEFAULT 0;
- DECLARE par_name varchar(64);
- DECLARE cur_partition_name CURSOR FOR SELECT partition_name FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA = tb_schema AND table_name = tb_name ORDER BY partition_ordinal_position;
- DECLARE CONTINUE HANDLER FOR SQLEXCEPTION, SQLWARNING, NOT FOUND SET _err = 1;
- DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;
- SET str_day = CONCAT('',part_value);
- OPEN cur_partition_name;
- REPEAT
- FETCH cur_partition_name INTO par_name;
- IF (str_day = SUBSTRING(par_name, 2)) THEN
-
- SET @alter_sql = CONCAT('alter table ', tb_name, ' drop PARTITION ', par_name);
- PREPARE stmt1 FROM @alter_sql;
- EXECUTE stmt1;
- END IF;
- UNTIL done END REPEAT;
- CLOSE cur_partition_name;
- END
- $$
（2）调用存储过程删除分区
删除分区
- CALL drop_list_partition(202201, 'test', 'list_part_table');
- CALL drop_list_partition(202202, 'test', 'list_part_table');
查看表的分区信息
- select * from information_schema.partitions where table_name like 'list_part_table%' ;
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