摘要：
要求：1。日志表需要按天进行分区。2.只保留一个月的数据。方案：1。创建两个事件，一个事件生成将来需要的分区，另一个事件定期检查过期数据（删除分区）。2.每小时创建一次事件，每天删除一次事件。3.在事件开始时，您需要首先创建当前所需的完整分区。方法：1。首先构造存储过程create_partition_Today：将表转换为分区表，并将历史数据收集到分区中，然后按天放置未来数据：#alter
需求:
1.日志表需要按天分区
2.只保留一个月数据
方案:
1.创建两个事件,一个事件生成未来需要的分区,另一个事件定期检查过期数据(移除分区)
2.创建事件每小时执行一次,删除事件每天执行一次
3.事件开始时需要先创建一个当前所需分区
全量方法:
1.先构造存储过程 create_partition_today :将表转化为分区表,并将历史数据归集到该分区,未来数据则按天放置:
#alter table to partition table DELIMITER $$ USE `dc_log`$$ DROP PROCEDURE IF EXISTS `create_partition_today`$$ CREATE PROCEDURE `create_partition_today`(IN_SCHEMANAME VARCHAR(64), IN_TABLENAME VARCHAR(64)) BEGIN DECLARE BEGINTIME TIMESTAMP; DECLARE ENDTIME TIMESTAMP; DECLARE DAYS_ENDTIME INT; DECLARE PARTITIONNAME VARCHAR(16); SET BEGINTIME = NOW(); SET ENDTIME = BEGINTIME + INTERVAL 1 DAY; SET PARTITIONNAME = DATE_FORMAT(BEGINTIME, 'p%Y%m%d'); SET DAYS_ENDTIME = TO_DAYS(ENDTIME); SET @SQL = CONCAT('ALTER TABLE `', IN_SCHEMANAME, '`.`', IN_TABLENAME, '`', ' PARTITION BY RANGE (to_days(create_time)) (PARTITION ', PARTITIONNAME, ' VALUES LESS THAN (', DAYS_ENDTIME, '))'); PREPARE STMT FROM @SQL; EXECUTE STMT; DEALLOCATE PREPARE STMT; END$$ DELIMITER ;
2.按天构造分区的存储过程create_partition_by_day:
#procedure of build partition of today and next day DELIMITER $$ USE `dc_log`$$ DROP PROCEDURE IF EXISTS `create_partition_by_day`$$ CREATE PROCEDURE `create_partition_by_day`(IN_SCHEMANAME VARCHAR(64), IN_TABLENAME VARCHAR(64)) BEGIN DECLARE ROWS_CNT INT UNSIGNED; DECLARE BEGINTIME TIMESTAMP; DECLARE ENDTIME TIMESTAMP; DECLARE DAYS_ENDTIME INT; DECLARE PARTITIONNAME VARCHAR(16); SET BEGINTIME = NOW() + INTERVAL 1 DAY; SET PARTITIONNAME = DATE_FORMAT(BEGINTIME, 'p%Y%m%d'); SET ENDTIME = BEGINTIME + INTERVAL 1 DAY; SET DAYS_ENDTIME = TO_DAYS(ENDTIME); SELECT COUNT(*) INTO ROWS_CNT FROM information_schema.partitions WHERE table_schema = IN_SCHEMANAME AND table_name = IN_TABLENAME AND partition_name = PARTITIONNAME; IF ROWS_CNT = 0 THEN SET @SQL = CONCAT('ALTER TABLE `', IN_SCHEMANAME, '`.`', IN_TABLENAME, '`', ' ADD PARTITION (PARTITION ', PARTITIONNAME, ' VALUES LESS THAN (', DAYS_ENDTIME, '))'); PREPARE STMT FROM @SQL; EXECUTE STMT; DEALLOCATE PREPARE STMT; ELSE SELECT CONCAT("partition `", PARTITIONNAME, "` for table `", IN_SCHEMANAME, ".", IN_TABLENAME, "` already exists") AS result; END IF; END$$ DELIMITER ;
3.按天清除数据的存储过程clear_partition_by_day
DELIMITER $$ USE `dc_log`$$ DROP PROCEDURE IF EXISTS `clear_partition_by_day`$$ CREATE PROCEDURE `clear_partition_by_day`(IN_SCHEMANAME VARCHAR(64), IN_TABLENAME VARCHAR(64)) BEGIN DECLARE NOWDAYS INT; DECLARE Done INT; DECLARE part VARCHAR(64); DECLARE descr INT; DECLARE rs CURSOR FOR SELECT partition_name part, partition_description descr FROM information_schema.partitions WHERE table_schema = IN_SCHEMANAME AND table_name = IN_TABLENAME; /* 异常处理 */ DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET Done = 1; OPEN rs; SET NOWDAYS = TO_DAYS(NOW()); FETCH rs into part,descr; while Done is null DO IF NOWDAYS - descr > 30 THEN select descr AS cc; SET @SQL = CONCAT('ALTER TABLE `', IN_SCHEMANAME, '`.`', IN_TABLENAME, '`', ' DROP PARTITION ', part); select descr AS aa; SELECT @SQL AS result; select descr AS bb; PREPARE STMT FROM @SQL; EXECUTE STMT; DEALLOCATE PREPARE STMT; END IF; FETCH rs into part,descr; end WHILE; CLOSE rs; END$$ DELIMITER ;
注意:以上过程有可能报错,这里记录两个错误:
1.分区字段必须包含主键:
这里采用的是事件字段作为分区字段,当然不可能是主键,所以再mysql中会报错,查阅资料大多说是因为分区表中不能保证数据唯一,需要将分区健纳入主键才可,不清楚原理.如果不愿意这样做也可以考虑,删除已有主键,无主键的表可以用任意字段作为分区字段
ALTER TABLE dc_system.service_push DROP PRIMARY KEY;
2.时间字段不允许作为分区字段:
这是因为 DATETIME 会受到时间区的影响,mysql里面分区的时间字段需要用CURRENT_TIMESTAMP
ALTER TABLE business_log MODIFY create_time DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP;
4.继续往下,打开事件变量,这里直接修改
SET GLOBAL event_scheduler = 'ON'; #打开
重启后会被重置,如果需要永久修改,在my.cnf（mysql配置文件）中[mysqld]部分中添加下面内容，重启MYSQL
event_scheduler=ON
5.调用存储过程创建当天分区:
#created today's partition CALL create_partition_today('dc_log', 'business_log');
6.创建事件:
DELIMITER $$ USE `dc_log`$$ CREATE EVENT IF NOT EXISTS `e_part_manage` ON SCHEDULE EVERY 1 HOUR #every minute STARTS '2018-05-01 18:27:00' ON COMPLETION PRESERVE ENABLE COMMENT 'Creating partitions' DO BEGIN CALL dc_log.create_partition_by_day('dc_log', 'business_log'); END$$ DELIMITER ; #event of clear data which out of date of 30 days DELIMITER $$ USE `dc_log`$$ CREATE EVENT IF NOT EXISTS `clear_data` ON SCHEDULE EVERY 1 DAY #every minute STARTS '2018-05-01 15:58:51' ON COMPLETION PRESERVE ENABLE COMMENT 'clearing data' DO BEGIN CALL clear_partition_by_day('dc_log', 'business_log'); END$$ DELIMITER ;
7.如果有其他表也需要如此处理,则先执行创建当天分区,再修改事件:
#service_push #same steps of table business_log ALTER TABLE dc_system.service_push DROP PRIMARY KEY; CALL create_partition_today('dc_system', 'service_push'); DELIMITER ; DELIMITER $$ ALTER EVENT e_part_manage DO BEGIN CALL dc_log.create_partition_by_day('dc_log', 'business_log'); CALL dc_log.create_partition_by_day('dc_system', 'service_push'); END$$ DELIMITER ; DELIMITER $$ ALTER EVENT clear_data DO BEGIN CALL dc_log.clear_partition_by_day('dc_log', 'business_log') ; CALL dc_log.clear_partition_by_day('dc_system', 'service_push'); END$$ DELIMITER ;
8.查看表的分区情况:
use dc_log; SELECT partition_name part, partition_expression expr, partition_description descr, table_rows FROM INFORMATION_SCHEMA.partitions WHERE TABLE_SCHEMA = SCHEMA() AND TABLE_NAME='service_push' ;
9.手动添加分区:
ALTER TABLE dc_log.all_log ADD PARTITION (PARTITION 'PARTITIONNAME' VALUES LESS THAN (TO_DAYS(now())));
10.查看事件和事件开关
show events; SHOW VARIABLES LIKE 'event_scheduler';
done