Mysql存储过程优化——使用临时表代替游标
2016-05-14 12:00
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MySQL游标在操作小数据量时比较方便,效率可观,但操作大数据量,速度比较慢,甚至直接产生系统错误。
一般说来,当操作的数据超过1万条时,就避免用游标吧。
为了测试游标性能,写了下面一个游标对IDC_Gather_Info表中数据进行遍历
Sql代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201908/04/10c4f8251144407653cad295a3d840e5.png)
CREATE DEFINER=`root`@`%` PROCEDURE `debug`(IN `beginTime` int, IN `checkTime` int)
BEGIN
DECLARE t_id VARCHAR(64) DEFAULT '';
DECLARE t_item TINYINT DEFAULT 0;
DECLARE t_result VARCHAR(8192) DEFAULT '';
DECLARE cursorDone INT DEFAULT 0;
DECLARE cur CURSOR FOR SELECT Asset_Id, Check_Item, Check_Result from IDC_Gather_Info WHERE Check_Time > beginTime AND Check_Time <= checkTime;
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET cursorDone = 1;
OPEN cur;
cursorLoop:LOOP
FETCH cur INTO t_id, t_item, t_result;
IF cursorDone = 1 THEN
LEAVE cursorLoop;
END IF;
END LOOP;
CLOSE cur;
END
下面是当表中数据分别为15万、5万、1万时游标的表现:
1.数据量15万,存储过程执行失败,提示错误:Incorrect key file for table '/tmp/#sql_3044_0.MYI';try to repair it
2.数据量5万,执行成功,耗时31.051s
3.数据量1万,执行成功,耗时1.371s
下面使用临时表替换游标:
Sql代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201908/04/10c4f8251144407653cad295a3d840e5.png)
CREATE DEFINER=`root`@`%` PROCEDURE `debug`(IN `beginTime` int, IN `checkTime` int)
BEGIN
DECLARE t_id VARCHAR(64) DEFAULT '';
DECLARE t_item TINYINT DEFAULT 0;
DECLARE t_result VARCHAR(8192) DEFAULT '';
DECLARE maxCnt INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DROP TABLE IF EXISTS Gather_Data_Tmp;
CREATE TEMPORARY TABLE Gather_Data_Tmp(
`Tmp_Id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`Asset_Id` VARCHAR(16) NOT NULL,
`Check_Item` TINYINT(1) NOT NULL,
`Check_Result` VARCHAR(8192) NOT NULL,
PRIMARY KEY (`Tmp_Id`)
)ENGINE=MyISAM DEFAULT CHARSET=utf8;
SET @tSql = CONCAT('INSERT INTO Gather_Data_Tmp (`Asset_Id`, `Check_Item`, `Check_Result`)
SELECT Asset_Id, Check_Item, Check_Result
FROM IDC_Gather_Info
WHERE Check_Time > ',beginTime,' AND Check_Time <= ',checkTime);
PREPARE gatherData FROM @tSql;
EXECUTE gatherData;
SELECT MIN(`Tmp_Id`) INTO i FROM Gather_Data_Tmp;
SELECT MAX(`Tmp_Id`) INTO maxCnt FROM Gather_Data_Tmp;
WHILE i <= maxCnt DO
SELECT Asset_Id, Check_Item, Check_Result INTO t_id, t_item, t_result FROM Gather_Data_Tmp WHERE Tmp_Id = i;
SET i = i + 1;
END WHILE;
END
1.数据量15万,执行成功,耗时8.928s
2.数据量5万,执行成功,耗时2.994s
3.数据量1万,执行成功,耗时0.634s
可以看到Mysql的游标在处理大一点的数据量时还是比较乏力的,仅适合用于操作几百上千的小数据量。
一般说来,当操作的数据超过1万条时,就避免用游标吧。
为了测试游标性能,写了下面一个游标对IDC_Gather_Info表中数据进行遍历
Sql代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201908/04/10c4f8251144407653cad295a3d840e5.png)
CREATE DEFINER=`root`@`%` PROCEDURE `debug`(IN `beginTime` int, IN `checkTime` int)
BEGIN
DECLARE t_id VARCHAR(64) DEFAULT '';
DECLARE t_item TINYINT DEFAULT 0;
DECLARE t_result VARCHAR(8192) DEFAULT '';
DECLARE cursorDone INT DEFAULT 0;
DECLARE cur CURSOR FOR SELECT Asset_Id, Check_Item, Check_Result from IDC_Gather_Info WHERE Check_Time > beginTime AND Check_Time <= checkTime;
DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET cursorDone = 1;
OPEN cur;
cursorLoop:LOOP
FETCH cur INTO t_id, t_item, t_result;
IF cursorDone = 1 THEN
LEAVE cursorLoop;
END IF;
END LOOP;
CLOSE cur;
END
下面是当表中数据分别为15万、5万、1万时游标的表现:
1.数据量15万,存储过程执行失败,提示错误:Incorrect key file for table '/tmp/#sql_3044_0.MYI';try to repair it
2.数据量5万,执行成功,耗时31.051s
3.数据量1万,执行成功,耗时1.371s
下面使用临时表替换游标:
Sql代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201908/04/10c4f8251144407653cad295a3d840e5.png)
CREATE DEFINER=`root`@`%` PROCEDURE `debug`(IN `beginTime` int, IN `checkTime` int)
BEGIN
DECLARE t_id VARCHAR(64) DEFAULT '';
DECLARE t_item TINYINT DEFAULT 0;
DECLARE t_result VARCHAR(8192) DEFAULT '';
DECLARE maxCnt INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DROP TABLE IF EXISTS Gather_Data_Tmp;
CREATE TEMPORARY TABLE Gather_Data_Tmp(
`Tmp_Id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`Asset_Id` VARCHAR(16) NOT NULL,
`Check_Item` TINYINT(1) NOT NULL,
`Check_Result` VARCHAR(8192) NOT NULL,
PRIMARY KEY (`Tmp_Id`)
)ENGINE=MyISAM DEFAULT CHARSET=utf8;
SET @tSql = CONCAT('INSERT INTO Gather_Data_Tmp (`Asset_Id`, `Check_Item`, `Check_Result`)
SELECT Asset_Id, Check_Item, Check_Result
FROM IDC_Gather_Info
WHERE Check_Time > ',beginTime,' AND Check_Time <= ',checkTime);
PREPARE gatherData FROM @tSql;
EXECUTE gatherData;
SELECT MIN(`Tmp_Id`) INTO i FROM Gather_Data_Tmp;
SELECT MAX(`Tmp_Id`) INTO maxCnt FROM Gather_Data_Tmp;
WHILE i <= maxCnt DO
SELECT Asset_Id, Check_Item, Check_Result INTO t_id, t_item, t_result FROM Gather_Data_Tmp WHERE Tmp_Id = i;
SET i = i + 1;
END WHILE;
END
1.数据量15万,执行成功,耗时8.928s
2.数据量5万,执行成功,耗时2.994s
3.数据量1万,执行成功,耗时0.634s
可以看到Mysql的游标在处理大一点的数据量时还是比较乏力的,仅适合用于操作几百上千的小数据量。
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