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
|
1
2
3
4
5
6
7
8
9
10
11
12
|
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
|
1
|
insert into metric_data_tmp select * from metric_data;
|
|
1
2
|
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：
|
1
2
|
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
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
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 ;
|
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
|
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
|
1
2
3
4
5
6
|
select
partition_name part,
partition_expression expr,
partition_description descr,
table_rows
from information_schema.partitions where table_name='metric_data';
|