MySQL-通过存储过程来添加和删除分区（List分区）

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%' ;

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%' ;