复杂的MySQL查询偶尔会运行非终止查询
每隔30分钟，我就会通过cron更新统计表，从PHP脚本运行一个相当复杂的SQL查询 通常情况下，更新工作正常，大约需要2-3分钟来处理大约40000条记录。通常，此查询运行无限长，长达数小时，没有结果。在PHPMyAdmin中查看MySQL进程，然后以50.000秒及以上的时间显示查询 这导致了一个问题，即该表不再整天更新。为什么会这样 查询很复杂，但不特殊：复杂的MySQL查询偶尔会运行非终止查询,mysql,performance,Mysql,Performance,每隔30分钟，我就会通过cron更新统计表，从PHP脚本运行一个相当复杂的SQL查询 通常情况下，更新工作正常，大约需要2-3分钟来处理大约40000条记录。通常，此查询运行无限长，长达数小时，没有结果。在PHPMyAdmin中查看MySQL进程，然后以50.000秒及以上的时间显示查询 这导致了一个问题，即该表不再整天更新。为什么会这样 查询很复杂，但不特殊： SELECT `a`.`id` AS `id`, `a`.`debitor`
SELECT `a`.`id`
AS
`id`,
`a`.`debitor`
AS `debitor`,
`a`.`wnummer`
AS `wnummer`,
`a`.`konto`
AS `konto`,
`a`.`datum`
AS `datum`,
`a`.`name`
AS `name`,
`a`.`name2`
AS `name2`,
`a`.`land`
AS `land`,
`a`.`plz`
AS `plz`,
`a`.`ort`
AS `ort`,
`a`.`str`
AS `str`,
`a`.`beschichterdatum`
AS `beschichterdatum`,
`a`.`werkstattdatum`
AS `werkstattdatum`,
`a`.`plandatum`
AS `plandatum`,
`a`.`kommision`
AS `kommision`,
`a`.`status`
AS `status`,
(SELECT `protokoll`.`ts`
FROM `protokoll`
WHERE ( `protokoll`.`auftrag_id` = `a`.`id` )
AND ( `protokoll`.`status_neu` = `a`.`status` )
ORDER BY `protokoll`.`ts` DESC
LIMIT 1)
AS `status_ts`,
`a`.`tourname`
AS `tourname`,
`a`.`anlage`
AS `anlage`,
`a`.`user`
AS `user`,
`a`.`vertreter`
AS `vertreter`,
`a`.`druckmodus`
AS `druckmodus`,
(SELECT GROUP_CONCAT(DISTINCT `position`.`maschine` ORDER BY
`position`.`maschine` ASC SEPARATOR ', ') AS
`maschine`
FROM `position`
WHERE ( `position`.`auftrag_id` = `a`.`id` )
AND ( `position`.`status` = 20 )
AND ( Length(`position`.`maschine`) > 0 ))
AS
`maschine`,
(SELECT GROUP_CONCAT(DISTINCT `position`.`beschichter` ORDER
BY
`position`.`beschichter` ASC SEPARATOR ', ') AS
`beschichter`
FROM `position`
WHERE ( `position`.`auftrag_id` = `a`.`id` )
AND ( `position`.`status` = 50 )
AND ( Length(`position`.`beschichter`) > 0 ))
AS
`beschichter`,
(SELECT DISTINCT `position`.`rueckstandinfo` AS
`rueckstandinfo`
FROM `position`
WHERE ( `position`.`auftrag_id` = `a`.`id` )
ORDER BY IF(( Length(`position`.`rueckstandinfo`) > 0 ), 1,
0) DESC
,
COUNT(*) DESC
LIMIT 1)
AS `rueckstandinfo`,
(SELECT COUNT(*)
FROM `position`
WHERE ( `position`.`auftrag_id` = `a`.`id` ))
AS `menge`,
(SELECT COUNT(*)
FROM `position`
WHERE ( `position`.`auftrag_id` = `a`.`id` )
AND ( `position`.`schrott` = 1 ))
AS `schrott`,
(SELECT SUM(`position`.`menge` -
`position`.`schrott`)
FROM `position`
WHERE ( ( `position`.`auftrag_id` = `a`.`id` )
AND ( ( CASE
WHEN ( `position`.`status` < 41 ) THEN (
To_days(`a`.`werkstattdatum`) - To_days(NOW()) )
WHEN ( `position`.`status` < 66 ) THEN (
To_days(`a`.`beschichterdatum`) - To_days(NOW()) )
WHEN ( `position`.`status` < 100 ) THEN (
To_days(`a`.`plandatum`) - To_days(NOW()) )
END ) < 0 ) ))
AS `rueckstaendig`,
( CASE
WHEN ( `a`.`status` < 41 ) THEN ( To_days(`a`.`werkstattdatum`) -
To_days(NOW()) )
WHEN ( `a`.`status` < 66 ) THEN (
To_days(`a`.`beschichterdatum`) - To_days(
NOW()) )
WHEN ( `a`.`status` < 100 ) THEN (
To_days(`a`.`plandatum`) - To_days(NOW())
)
END )
AS `kalendertage`
FROM `auftrag` `a`
但我肯定会尽可能用JOIN和GROUP BY替换select部分中的子查询——select中的子查询必须为每一行计算。例如，在我看来，Menge和Schrott列似乎很容易替换。以下是我将尝试做的。。。通过提取子查询，我能够将3个元素包装到一个查询/连接结果中。无法应用于处理limit 1实例，因此将它们保留为在线选择
SELECT
a.id,
a.debitor,
a.wnummer,
a.konto,
a.datum,
a.`name`,
a.name2,
a.land,
a.plz,
a.ort,
a.`str`,
a.beschichterdatum,
a.werkstattdatum,
a.plandatum,
a.kommision,
a.`status`,
( SELECT protokoll.ts
FROM protokoll
WHERE ( protokoll.auftrag_id = a.id )
AND ( protokoll.status_neu = a.`status` )
ORDER BY protokoll.ts DESC
LIMIT 1) AS status_ts,
a.tourname,
a.anlage,
a.`user`,
a.vertreter,
a.druckmodus,
JoinMaschine.maschine,
JoinBeschichter.beschichter,
MengeSchrottRueck.menge,
MengeSchrottRueck.schrott,
MengeSchrottRueck.rueckstaendig,
( SELECT DISTINCT `position`.rueckstandinfo AS rueckstandinfo
FROM `position`
WHERE ( `position`.auftrag_id = a.id )
ORDER BY
IF(( Length(`position`.rueckstandinfo) > 0 ), 1, 0) DESC,
COUNT(*) DESC
LIMIT 1 ) AS rueckstandinfo,
( CASE WHEN ( a.`status` < 41 )
THEN ( To_days(a.werkstattdatum) - To_days(NOW()) )
WHEN ( a.`status` < 66 )
THEN ( To_days(a.beschichterdatum) - To_days( NOW()) )
WHEN ( a.`status` < 100 )
THEN (To_days(a.plandatum) - To_days(NOW()) )
END ) AS kalendertage
FROM
auftrag a
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.maschine
ORDER BY p.maschine ASC SEPARATOR ', ') AS maschine
from `position` p
WHERE p.`status` = 20
AND Length(p.maschine) > 0
group by p.auftrag_id ) as JoinMaschine
ON a.ID = JoinMaschine.auftrag_id
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.beschichter
ORDER BY p.beschichter ASC SEPARATOR ', ') AS beschichter
FROM `position` p
WHERE ( `position`.auftrag_id = a.id )
AND ( `position`.`status` = 50 )
AND ( Length(`position`.beschichter) > 0 )
GROUP BY p.auftrag_id ) AS JoinBeschichter
ON a.id = JoinBeschichter.auftrag_id
JOIN ( SELECT p.auftrag_id,
COUNT(*) as Menge,
SUM( IF( p.schrott = 1, 1, 0 )) as schrott,
SUM(p.menge - p.schrott *
IF( ( p.`status` < 41 AND To_days(a.werkstattdatum) - To_days(NOW()) < 0)
OR ( p.`status` < 66 AND To_days(a.beschichterdatum) - To_days(NOW()) < 0 )
OR ( p.`status` < 100 AND To_days(a.plandatum) - To_days(NOW()) < 0 ), 1, 0 )
) AS rueckstaendig
FROM `position` p
group by p.auftrag_id ) as MengeSchrottRueck
ON a.id = MengeSchrottRueck.auftrag_id
以下是我将尝试做的。。。通过提取子查询，我能够将3个元素包装到一个查询/连接结果中。无法应用于处理limit 1实例，因此将它们保留为在线选择
SELECT
a.id,
a.debitor,
a.wnummer,
a.konto,
a.datum,
a.`name`,
a.name2,
a.land,
a.plz,
a.ort,
a.`str`,
a.beschichterdatum,
a.werkstattdatum,
a.plandatum,
a.kommision,
a.`status`,
( SELECT protokoll.ts
FROM protokoll
WHERE ( protokoll.auftrag_id = a.id )
AND ( protokoll.status_neu = a.`status` )
ORDER BY protokoll.ts DESC
LIMIT 1) AS status_ts,
a.tourname,
a.anlage,
a.`user`,
a.vertreter,
a.druckmodus,
JoinMaschine.maschine,
JoinBeschichter.beschichter,
MengeSchrottRueck.menge,
MengeSchrottRueck.schrott,
MengeSchrottRueck.rueckstaendig,
( SELECT DISTINCT `position`.rueckstandinfo AS rueckstandinfo
FROM `position`
WHERE ( `position`.auftrag_id = a.id )
ORDER BY
IF(( Length(`position`.rueckstandinfo) > 0 ), 1, 0) DESC,
COUNT(*) DESC
LIMIT 1 ) AS rueckstandinfo,
( CASE WHEN ( a.`status` < 41 )
THEN ( To_days(a.werkstattdatum) - To_days(NOW()) )
WHEN ( a.`status` < 66 )
THEN ( To_days(a.beschichterdatum) - To_days( NOW()) )
WHEN ( a.`status` < 100 )
THEN (To_days(a.plandatum) - To_days(NOW()) )
END ) AS kalendertage
FROM
auftrag a
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.maschine
ORDER BY p.maschine ASC SEPARATOR ', ') AS maschine
from `position` p
WHERE p.`status` = 20
AND Length(p.maschine) > 0
group by p.auftrag_id ) as JoinMaschine
ON a.ID = JoinMaschine.auftrag_id
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.beschichter
ORDER BY p.beschichter ASC SEPARATOR ', ') AS beschichter
FROM `position` p
WHERE ( `position`.auftrag_id = a.id )
AND ( `position`.`status` = 50 )
AND ( Length(`position`.beschichter) > 0 )
GROUP BY p.auftrag_id ) AS JoinBeschichter
ON a.id = JoinBeschichter.auftrag_id
JOIN ( SELECT p.auftrag_id,
COUNT(*) as Menge,
SUM( IF( p.schrott = 1, 1, 0 )) as schrott,
SUM(p.menge - p.schrott *
IF( ( p.`status` < 41 AND To_days(a.werkstattdatum) - To_days(NOW()) < 0)
OR ( p.`status` < 66 AND To_days(a.beschichterdatum) - To_days(NOW()) < 0 )
OR ( p.`status` < 100 AND To_days(a.plandatum) - To_days(NOW()) < 0 ), 1, 0 )
) AS rueckstaendig
FROM `position` p
group by p.auftrag_id ) as MengeSchrottRueck
ON a.id = MengeSchrottRueck.auftrag_id
如果您的查询在大部分时间都有效，那么一些外力正在影响它。您还运行了哪些其他cron作业？运行查询时是否正在运行其他数据库查询？插入/查询是否包装在事务中 因此，我的建议是： 在PHP脚本中使用事务
尝试一种非默认锁定模式。MySQL的默认设置是可重复读取。如果脏读很好，请尝试“未提交读取”，或者如果不可接受，请尝试“更酸的已提交读取” 如果您的查询在大部分时间都有效，那么一些外力会影响它。您还运行了哪些其他cron作业？运行查询时是否正在运行其他数据库查询？插入/查询是否包装在事务中 因此，我的建议是： 在PHP脚本中使用事务
尝试一种非默认锁定模式。MySQL的默认设置是可重复读取。如果脏读很好，请尝试“未提交读取”，或者如果不可接受，请尝试“更酸的已提交读取” 我建议您强制执行解释中显示的所有索引。
有时mysql会认为没有索引更好，因此您的时间更长。我建议您强制执行解释中显示的所有索引。
有时mysql会认为没有索引更好，因此您会得到更长的时间。您可以通过在相同的字段上不使用as子句将行减半。您可以共享您的模式吗？另一个可能很重要的辅助信息：查询封装在INSERT语句中，该语句将此查询的结果插入到一个表中，该表与所选字段具有相同的模式，但有自己的索引。无限运行可能来自insert/在insert期间创建索引吗？您可以在相同的字段上不使用as子句将行切成两半。您可以共享您的模式吗？另一个可能很重要的辅助信息：查询封装在INSERT语句中，该语句将此查询的结果插入到一个表中，该表与所选字段具有相同的模式，但有自己的索引。无限运行可能来自插入/插入期间索引的创建吗？是的，也许你是对的。通过使用联接，查询的运行速度可能超过两分钟。但问题是，查询偶尔会无限运行，持续数小时/天，这与查询优化或用我的连接替换子查询无关。根据我的意见…-请参阅我更新的问题以了解解释输出。是的，也许你是对的。通过使用联接，查询的运行速度可能超过两分钟。但问题是，查询偶尔会无限运行，持续数小时/天，这与查询优化或用我的连接替换子查询无关。根据我的意见…-有关解释输出，请参阅我更新的问题。
CREATE TABLE `protokoll`
(
`id` INT(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
`usr_id` INT(11) NOT NULL COMMENT 'Benutzer',
`auftrag_id` INT(11) NOT NULL COMMENT 'Auftrag',
`pos_id` INT(11) NOT NULL COMMENT 'Position',
`artikel_id` VARCHAR(255) NOT NULL COMMENT 'Artikel',
`status_alt` SMALLINT(6) DEFAULT NULL COMMENT 'Status ALT',
`status_neu` SMALLINT(6) DEFAULT NULL COMMENT 'status NEU',
`info` VARCHAR(255) DEFAULT NULL COMMENT 'Infotext',
`ts` DATETIME NOT NULL COMMENT 'Zeitstempel',
PRIMARY KEY (`id`),
KEY `ts` (`ts`),
KEY `auftrag_id_2` (`auftrag_id`, `artikel_id`, `status_neu`)
)
ENGINE=myisam
AUTO_INCREMENT=361183
DEFAULT CHARSET=utf8
SELECT
a.id,
a.debitor,
a.wnummer,
a.konto,
a.datum,
a.`name`,
a.name2,
a.land,
a.plz,
a.ort,
a.`str`,
a.beschichterdatum,
a.werkstattdatum,
a.plandatum,
a.kommision,
a.`status`,
( SELECT protokoll.ts
FROM protokoll
WHERE ( protokoll.auftrag_id = a.id )
AND ( protokoll.status_neu = a.`status` )
ORDER BY protokoll.ts DESC
LIMIT 1) AS status_ts,
a.tourname,
a.anlage,
a.`user`,
a.vertreter,
a.druckmodus,
JoinMaschine.maschine,
JoinBeschichter.beschichter,
MengeSchrottRueck.menge,
MengeSchrottRueck.schrott,
MengeSchrottRueck.rueckstaendig,
( SELECT DISTINCT `position`.rueckstandinfo AS rueckstandinfo
FROM `position`
WHERE ( `position`.auftrag_id = a.id )
ORDER BY
IF(( Length(`position`.rueckstandinfo) > 0 ), 1, 0) DESC,
COUNT(*) DESC
LIMIT 1 ) AS rueckstandinfo,
( CASE WHEN ( a.`status` < 41 )
THEN ( To_days(a.werkstattdatum) - To_days(NOW()) )
WHEN ( a.`status` < 66 )
THEN ( To_days(a.beschichterdatum) - To_days( NOW()) )
WHEN ( a.`status` < 100 )
THEN (To_days(a.plandatum) - To_days(NOW()) )
END ) AS kalendertage
FROM
auftrag a
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.maschine
ORDER BY p.maschine ASC SEPARATOR ', ') AS maschine
from `position` p
WHERE p.`status` = 20
AND Length(p.maschine) > 0
group by p.auftrag_id ) as JoinMaschine
ON a.ID = JoinMaschine.auftrag_id
JOIN ( SELECT p.auftrag_id,
GROUP_CONCAT(DISTINCT p.beschichter
ORDER BY p.beschichter ASC SEPARATOR ', ') AS beschichter
FROM `position` p
WHERE ( `position`.auftrag_id = a.id )
AND ( `position`.`status` = 50 )
AND ( Length(`position`.beschichter) > 0 )
GROUP BY p.auftrag_id ) AS JoinBeschichter
ON a.id = JoinBeschichter.auftrag_id
JOIN ( SELECT p.auftrag_id,
COUNT(*) as Menge,
SUM( IF( p.schrott = 1, 1, 0 )) as schrott,
SUM(p.menge - p.schrott *
IF( ( p.`status` < 41 AND To_days(a.werkstattdatum) - To_days(NOW()) < 0)
OR ( p.`status` < 66 AND To_days(a.beschichterdatum) - To_days(NOW()) < 0 )
OR ( p.`status` < 100 AND To_days(a.plandatum) - To_days(NOW()) < 0 ), 1, 0 )
) AS rueckstaendig
FROM `position` p
group by p.auftrag_id ) as MengeSchrottRueck
ON a.id = MengeSchrottRueck.auftrag_id