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我已经在我的数据库服务器上设置了 mysql 慢查询日志并将长查询时间设置为 5。刚刚检查了日志及其日志查询，只需要几毫秒。有人知道为什么会这样吗？，这是一些日志。

最后一个查询并不是最优化的。它说它检查了 450000 行，所以在日志中看到它我不会感到惊讶。然而查询时间说它只花了0.2秒。除了查询执行时间之外，还有更多的慢查询日志吗？

# Query_time: 0.000525  Lock_time: 0.000151 Rows_sent: 1  Rows_examined: 115
SET timestamp=1349393722;
SELECT `we_members`.*, `we_referrals`.`code` as referral_code
FROM (`we_members`)
LEFT JOIN `we_referrals` ON `we_referrals`.`m_id` = `we_members`.`id`
WHERE `we_members`.`facebook_id` = '100'
LIMIT 1;

# Query_time: 0.000748  Lock_time: 0.000104 Rows_sent: 3  Rows_examined: 691
SET timestamp=1349393722;
select distinct(m_id), m.first_name, m.facebook_id, m.photo_url from
            we_connections f
            left join we_members m on m.id = f.m_id
            where ( (f.friend_id = 75 or f.m_id = 75 and m.id != 75))
            and m.id >0
            and m.id != 75
            order by m_id;

# Query_time: 0.259535  Lock_time: 0.000098 Rows_sent: 16  Rows_examined: 455919
SET timestamp=1349393722;
select distinct(m_id), m.first_name, m.facebook_id, m.photo_url from
            we_connections f
            left join we_members m on m.id = f.m_id
            where (f.friend_id IN (select friend_id from we_connections f where f.m_id = 75) or (f.friend_id = 75 or f.m_id = 75 and m.id != 75))
            and m.id >0
            and m.id != 75
            order by m_id;
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1 回答 1

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鉴于在某些查询中检查了大量行，您可能也log_queries_not_using_indexes设置了选项 - 任何不使用索引的查询也将写入慢查询日志。您可以在my.cnf文件中检查此选项。

http://dev.mysql.com/doc/refman/5.5/en/server-options.html#option_mysqld_log-queries-not-using-indexes

有关写入日志的查询类型的更多信息http://dev.mysql.com/doc/refman/5.5/en/slow-query-log.html

于 2012-10-05T00:29:04.963 回答