MySQL实现清空分区表单个分区数据

MySQL清空分区表单个分区数据

1.单个分区清空

ALTER TABLE xxx TRUNCATE PARTITION p20220104；

2.编辑存储过程

功能：指定清空之前某一天的数据，直接调用存储过程实现

DELIMITER $$

USE `managerdb`$$

DROP PROCEDURE IF EXISTS `partition_trunc`$$

CREATE DEFINER=`root`@`localhost` PROCEDURE `partition_trunc`(p_schema_name VARCHAR(64), p_table_name VARCHAR(64), p_trunc_before_date INT)
BEGIN
/*
p_trunc_before_date 清空分区表第N天的数据
*/      
       DECLARE trunc_part_name VARCHAR(16);

SET trunc_part_name = CONCAT('p',DATE_FORMAT(DATE_SUB(CURDATE(),INTERVAL p_trunc_before_date DAY),'％Y％m％d'));
       SET @trunc_partitions = CONCAT("ALTER TABLE ", p_schema_name, ".", p_table_name, " TRUNCATE PARTITION ",trunc_part_name); -- 拼执行语句

SELECT @trunc_partitions; -- 打印删除详情

PREPARE STMT FROM @trunc_partitions;

EXECUTE STMT;

DEALLOCATE PREPARE STMT;

END$$

DELIMITER ;

实例：

call managerdb.partition_trunc('test','t_001',1);

清空test.t_001一天前的单个分区数据

MySQL自动分区自动清理

mysql分区表功能特别有用，其中一个应用就是保存固定时间的数据信息，自动分区自动purge，不用担心数据量越积累越多。

比较实用的一个实现方式是表一天一个分区，保持固定天数的数据。

完整的SQL

以数据库log为例，里面有一个表tb_log, 按天分区，始终保存最新的30天的数据。

存储过程sp_create_log_partition和sp_drop_log_partition用于创建和删除分区。

事件event_log_auto_partition每天执行一次，用于向前创建新的分区和删除过期的分区。

存储过程和事件结合使用就实现了tb_log数据的自动分区自动删除。

--
-- Definition for database log
--
DROP DATABASE IF EXISTS log;
CREATE DATABASE IF NOT EXISTS log
CHARACTER SET utf8
COLLATE utf8_general_ci;

--
-- Set default database
--
USE log;

--
-- Definition for table tb_log
--
CREATE TABLE IF NOT EXISTS tb_log (
 id bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT,
 created_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
 log varchar(512) NOT NULL DEFAULT '',
 PRIMARY KEY (id, created_at)
)
ENGINE = INNODB
AUTO_INCREMENT = 1
AVG_ROW_LENGTH = 16384
CHARACTER SET utf8mb4
COLLATE utf8mb4_general_ci
PARTITION BY RANGE(TO_DAYS(created_at))
(
PARTITION pbasic VALUES LESS THAN (0)
);

DELIMITER $$

--
-- Definition for procedure sp_create_log_partition
--
CREATE DEFINER = 'uiadmin'@'％'
PROCEDURE sp_create_log_partition (day_value datetime, tb_name varchar(128))
BEGIN
 DECLARE par_name varchar(32);
 DECLARE par_value varchar(32);
 DECLARE _err int(1);
 DECLARE par_exist int(1);
 DECLARE CONTINUE HANDLER FOR SQLEXCEPTION, SQLWARNING, NOT FOUND SET _err = 1;
 START TRANSACTION;
   SET par_name = CONCAT('p', DATE_FORMAT(day_value, '％Y％m％d'));
   SELECT
     COUNT(1) INTO par_exist
   FROM information_schema.PARTITIONS
   WHERE TABLE_SCHEMA = 'log' AND TABLE_NAME = tb_name AND PARTITION_NAME = par_name;
   IF (par_exist = 0) THEN
     SET par_value = DATE_FORMAT(day_value, '％Y-％m-％d');
     SET @alter_sql = CONCAT('alter table ', tb_name, ' add PARTITION (PARTITION ', par_name, ' VALUES LESS THAN (TO_DAYS("', par_value, '")+1))');
     PREPARE stmt1 FROM @alter_sql;
     EXECUTE stmt1;
   END IF;
 END
 $$

--
-- Definition for procedure sp_drop_log_partition
--
CREATE DEFINER = 'uiadmin'@'％'
PROCEDURE sp_drop_log_partition (day_value datetime, 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 = 'log' 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 = DATE_FORMAT(day_value, '％Y％m％d');
 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
$$

--
-- Definition for event event_log_auto_partition
--
CREATE
DEFINER = 'uiadmin'@'％'
EVENT event_log_auto_partition
ON SCHEDULE EVERY '1' DAY
STARTS '1972-01-01 00:00:00'
ON COMPLETION PRESERVE
DO
BEGIN
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 3 DAY), 'tb_log');
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 2 DAY), 'tb_log');
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 1 DAY), 'tb_log');
 CALL sp_create_log_partition(NOW(), 'tb_log');
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 1 DAY), 'tb_log');
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 2 DAY), 'tb_log');
 CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 3 DAY), 'tb_log');
 CALL sp_drop_log_partition(DATE_ADD(NOW(), INTERVAL - 30 DAY), 'tb_log');

END
$$

--
-- Create partitions based on current time
--
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 3 DAY), 'tb_log')$$
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 2 DAY), 'tb_log')$$
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL - 1 DAY), 'tb_log')$$
CALL sp_create_log_partition(NOW(), 'tb_log')$$
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 1 DAY), 'tb_log')$$
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 2 DAY), 'tb_log')$$
CALL sp_create_log_partition(DATE_ADD(NOW(), INTERVAL 3 DAY), 'tb_log')$$

DELIMITER ;

查看分区

select TABLE_SCHEMA, TABLE_NAME,PARTITION_NAME from INFORMATION_SCHEMA.PARTITIONS where TABLE_SCHEMA='log' and table_name='tb_log';

在磁盘上一个分区表现为一个文件，所以删除操作会很快完成的。

来源：https://blog.csdn.net/demonson/article/details/127683373