Mysql分区表及自动创建分区Partition

Posted 2020-11-20 骑着龙的羊

Range分区表建表语句如下，其中分区键必须和id构成主键和唯一键

CREATE TABLE `test1` (
  `id` char(32) COLLATE utf8mb4_unicode_ci NOT NULL COMMENT ‘自增主键(guid)‘,
  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT ‘创建时间‘,
  `partition_key` int(8) NOT NULL COMMENT ‘分区键(格式:yyyyMMdd)‘,
  PRIMARY KEY (`id`,`partition_key`),
  UNIQUE KEY `id_UNIQUE` (`id`,`partition_key`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
PARTITION BY RANGE (partition_key)
(PARTITION p0 VALUES LESS THAN (20180619) ENGINE = InnoDB,
 PARTITION p20180619 VALUES LESS THAN (20180620) ENGINE = InnoDB,
 PARTITION p20180621 VALUES LESS THAN (20180622) ENGINE = InnoDB,
 PARTITION p20180622 VALUES LESS THAN (20180623) ENGINE = InnoDB,
 PARTITION p20180623 VALUES LESS THAN (20180624) ENGINE = InnoDB);　

新增分区

alter TABLE `test1` add PARTITION(
 PARTITION p20180629 VALUES LESS THAN (20180630) ENGINE = InnoDB
);

删除分区

alter table `test1`  drop PARTITION p20180629;

 

mysql不能自动创建分区，需要使用mysql event事件的方式自动创建分区

1.创建分区的存储过程如下（每次执行先校验当前分区是否存在，如果存在则不处理；不存在则创建）：

DELIMITER $$
#该表所在数据库名称
USE `demo`$$
DROP PROCEDURE IF EXISTS `create_partition_by_day`$$
CREATE PROCEDURE `create_partition_by_day`(IN_SCHEMANAME VARCHAR(64), IN_TABLENAME VARCHAR(64))
BEGIN
    #当前日期存在的分区的个数
    DECLARE ROWS_CNT INT UNSIGNED;
    #目前日期，为当前日期的后一天
    DECLARE TARGET_DATE TIMESTAMP;
    #分区的名称，格式为p20180620
    DECLARE PARTITIONNAME VARCHAR(9);
    #当前分区名称的分区值上限，即为 PARTITIONNAME + 1
    DECLARE PARTITION_ADD_DAY VARCHAR(9);
    SET TARGET_DATE = NOW() + INTERVAL 1 DAY;
    SET PARTITIONNAME = DATE_FORMAT( TARGET_DATE, ‘p%Y%m%d‘ );
    SET TARGET_DATE = TARGET_DATE + INTERVAL 1 DAY;
    SET PARTITION_ADD_DAY = DATE_FORMAT( TARGET_DATE, ‘%Y%m%d‘ );
    SELECT COUNT(*) INTO ROWS_CNT FROM information_schema.partitions
	WHERE table_schema = IN_SCHEMANAME AND table_name = IN_TABLENAME AND partition_name = PARTITIONNAME;
    IF ROWS_CNT = 0 THEN
        SET @SQL = CONCAT( ‘ALTER TABLE `‘, IN_SCHEMANAME, ‘`.`‘, IN_TABLENAME, ‘`‘,
	    ‘ ADD PARTITION (PARTITION ‘, PARTITIONNAME, " VALUES LESS THAN (", 
            PARTITION_ADD_DAY ,") ENGINE = InnoDB);" );
        PREPARE STMT FROM @SQL;
        EXECUTE STMT;
        DEALLOCATE PREPARE STMT;
     ELSE
	   SELECT CONCAT("partition `", PARTITIONNAME, "` for table `",IN_SCHEMANAME, ".", IN_TABLENAME, "` already exists") AS result;
     END IF;
END$$
DELIMITER ;

2.数据库定时任务(每小时执行一次)

DELIMITER $$
#该表所在的数据库名称
USE `demo`$$
CREATE EVENT IF NOT EXISTS `daily_generate_partition`
ON SCHEDULE EVERY 1 hour   #执行周期，还有天、月等等
STARTS ‘2018-06-20 00:00:00‘
ON COMPLETION PRESERVE
ENABLE
COMMENT ‘Creating partitions‘
DO BEGIN
    #调用刚才创建的存储过程，第一个参数是数据库名称，第二个参数是表名称
    CALL datacollectcenter.create_partition_by_day(‘demo‘,‘test1‘);
END$$
DELIMITER ;