blocks|key|4749104|text|我认为清理工作中最繁重的任务是删除操作，您可以使用LOW_PRIORITY来完成该操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4749105|从MySql+manual+page中删除语法|offset|length|4749106|4749107|从tbl_name中删除LOW_PRIORITY+QUICK+...|blockquote|style|BOLD|4749108|4749109|4749110|和描述：|4749111|4749112|如果指定LOW_PRIORITY，则服务器会延迟执行删除操作，直到没有其他客户端正在从表中读取数据。这只会影响只使用表级锁定的存储引擎(如MyISAM、内存和合并)。|4749113|4749114|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/5.0/en/delete.html^0|0|7|B|0|0|0|C|C|0|0|0|0|0|4|C|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|12|8|@]|9|@$D|13|E|14|1|15]]|A|$]]|$1|F|3|-4|5|6|7|16|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|17|8|@$D|18|E|19|J|K]]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|1C|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|Q|3|R|5|I|7|1E|8|@$D|1F|E|1G|J|K]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|U|$V|$5|W|X|Y|A|$Z|10]]]]

I think the heaviest task in your cleanup is the DELETE operation for which you can use LOW_PRIORITY.

DELETE syntax from MySql <a href="http://dev.mysql.com/doc/refman/5.0/en/delete.html" rel="nofollow">manual page</a>:

<blockquote>
 DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name ...
</blockquote>

and the description:

<blockquote>
 If you specify LOW_PRIORITY, the server delays execution of the DELETE until no other clients are reading from the table. This affects only storage engines that use only table-level locking (such as MyISAM, MEMORY, and MERGE).
</blockquote>

blocks|key|655346|text|在MYSQL中有一种叫做低优先级更新的东西，它的文档记录在->+http://dev.mysql.com/doc/refman/5.5/en/server-options.html#option_mysqld_low-priority-updates中。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|655347|**仅适用于MyISAM、内存、合并存储引擎....|655348|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/5.5/en/server-options.html#option_mysqld_low-priority-updates^0|W|2L|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

There is such a thing in MYSQL as low-priority-updates - its documented here -> <a href="http://dev.mysql.com/doc/refman/5.5/en/server-options.html#option_mysqld_low-priority-updates" rel="nofollow">http://dev.mysql.com/doc/refman/5.5/en/server-options.html#option_mysqld_low-priority-updates</a>

** only works for MyISAM, MEMORY, MERGE storage engines ....

blocks|key|658007|text|MYSQL中的低优先级请求之一是INSERT+DELAYED。但它只适用于插入，而不适用于更新或删除。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|658008|编辑:我只知道删除也可以延迟！|658009|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/5.5/en/insert-delayed.html^0|G|E|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

One of the low priority requests in MYSQL is <a href="http://dev.mysql.com/doc/refman/5.5/en/insert-delayed.html" rel="nofollow">INSERT DELAYED</a>. But it only works on INSERT, not UPDATE or DELETE.

EDIT: I just knew that DELETE also can be delayed!

blocks|key|4749027|text|一种可能的解决方案是在从属复制服务器上复制旧数据。这样一来，沉重的负载就完全落在了那个从属机器上。在从服务器上完成复制后，您可以在主服务器上删除。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4749028|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

One possible solution would be to do the copying of old data on a slaved replication server. That way, the heavy load is entirely on that slave box. Once the copying is finished on slave, you could delete on master.

blocks|key|658046|text|正如the+documentation中所解释的，您可以将LOW_PRIORITY添加到查询中。因此，您的查询将变为：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|658047|$sql+=+"INSERT+LOW_PRIORITY+INTO+#__bet_oddslog+(id,+team1,+team2,+league,+sport,+time,+q1,+q2)";+$sql+.=+"+SELECT+a.id,+a.team1,+a.team2,+a.league,+a.sport,+a.time,+AVG(b.q1)+as+q1,+";+$sql+.=+"+AVG(b.q2)+as+q2+FROM+#__bet_details+as+a,+#__bet_1x2_best+as+b+WHERE+time<'".date('Y-m-d+H:i:s',+strtotime("now"))."'+AND+a.id=b.bet_id+GROUP+BY+b.bet_id";|code-block|syntax|javascript|658048|entityMap|0|LINK|mutability|MUTABLE|url|http://dev.mysql.com/doc/refman/5.6/en/insert-select.html^0|T|C|2|H|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

As explained in <a href="http://dev.mysql.com/doc/refman/5.6/en/insert-select.html" rel="nofollow">the documentation</a>, you could add <code>LOW_PRIORITY</code> to your query. So, your query would become:

<pre><code>$sql = "INSERT LOW_PRIORITY INTO #__bet_oddslog (id, team1, team2, league, sport, time, q1, q2)"; $sql .= " SELECT a.id, a.team1, a.team2, a.league, a.sport, a.time, AVG(b.q1) as q1, "; $sql .= " AVG(b.q2) as q2 FROM #__bet_details as a, #__bet_1x2_best as b WHERE time&lt;'".date('Y-m-d H:i:s', strtotime("now"))."' AND a.id=b.bet_id GROUP BY b.bet_id";
</code></pre>

I Have a site and a database with 5 million rows, it's working like a charm. However, I'm running a cleanup cronjob each hour, to put the old data to a 'log' table and delete the old data, and in this time the server response is very slow. Is it possible to give that job a lower priority via PHP or MySQL?

Low priority request in PHP or MySQL

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个网站和一个有500万行的数据库，它的运行效果非常好。但是，我每小时运行一次清理cronjob，将旧数据放到'log‘表中并删除旧数据，此时服务器响应非常慢。有没有可能通过PHP或MySQL给该作业一个较低的优先级？

问PHP或MySQL中的低优先级请求
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回答 5

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