MySQL大数据表水平分区优化的详细步骤
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2022-03-24 23:37:11
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将运行中的大表修改为分区表
本文章代码仅限于以数据时间按月水平分区,其他需求可自行修改代码实现
1. 创建一张分区表
这张表的表字段和原表的字段一摸一样,附带分区
CREATE TABLE `metric_data_tmp` ( id bigint primary key auto_increment, metric varchar(128), datadt datetime not null unqine, value decimal(30, 6) ) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8 partition by range (to_days(DATADT)) ( PARTITION p201811 VALUES LESS THAN (to_days("2018-12-01")), PARTITION p201812 VALUES LESS THAN (to_days("2019-01-01")), PARTITION p201901 VALUES LESS THAN (to_days("2019-02-01")), PARTITION p201902 VALUES LESS THAN (to_days("2019-03-01")), );
2. 将原表数据复制到临时表
直接通过
insert
语句
insert into metric_data_tmp select * from metric_data;
数据量非常大,可使用
select into outfile, Load data file
方式导出导入
SELECT * INTO OUTFILE 'data.txt' FIELDS TERMINATED BY ',' FROM metric_data; LOAD DATA INFILE 'data.txt' INTO TABLE metric_data_tmp FIELDS TERMINATED BY ',';
3. 重命名分区表和历史表:
rename table metric_data to metric_data_bak; rename table metric_data_tmp to metric_data;
4. 通过数据库的定时任务定时自动创建下月的分区
存储过程
delimiter $$ use `db_orbit`$$ drop procedure if exists `create_partition_by_month`$$ create procedure `create_partition_by_month`(in_schemaname varchar(64), in_tablename varchar(64)) begin # 用于判断需要创建的表分区是否已经存在 declare rows_cnt int unsigned; # 要创建表分区的时间 declare target_date timestamp; #分区的名称,格式为p201811 declare partition_name varchar(8); #要创建的分区时间为下个月 set target_date = date_add(now(), interval 1 month); set partition_name = date_format( target_date, 'p%Y%m' ); # 判断要创建的分区是否存在 select count(1) into rows_cnt from information_schema.partitions t where table_schema = in_schemaname and table_name = in_tablename and ifnull(t.partition_name, '') = partition_name; if rows_cnt = 0 then set @sql = concat( 'alter table `', in_schemaname, '`.`', in_tablename, '`', ' add partition (partition ', partition_name, " values less than (to_days('", date_format(DATE_ADD(target_date, INTERVAL 1 month), '%Y-%m-01'), "')) engine = innodb);" ); prepare stmt from @sql; execute stmt; deallocate prepare stmt; else select concat("partition `", partition_name, "` for table `",in_schemaname, ".", in_tablename, "` already exists") as result; end if; end$$ delimiter ;
创建定时任务,定时执行存储过程创建分区
DELIMITER $$ #该表所在的数据库名称 USE `db_orbit`$$ CREATE EVENT IF NOT EXISTS `generate_partition_for_metric_data` ON SCHEDULE EVERY 1 MONTH #执行周期,还有天、月等等 STARTS '2019-03-15 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 db_orbit.create_partition_by_month('db_orbit', 'metric_data'); END$$ DELIMITER ;
5.其他
查看表分区情况的SQL
select partition_name part, partition_expression expr, partition_description descr, table_rows from information_schema.partitions where table_name='metric_data';
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