MySQL性能优化实战
2009-04-21 11:17:26 来源:WEB开发网然后发挥您的想象力在这个表中尽力捕捉你想捕捉的,那类型语句压力最大、扫描行数最多、等锁最久……
比如:
优化后:
mysql> select sum(query_time)/count(*),count
(*),sum(query_time),min(Date),Max(Date) from slow where Date>'2008-02-20 22:50:52'
and Date<'2008-02-21 17:34:35';
+--------------------------+----------+-----------------+---------------------+---------------------+
| sum(query_time)/count(*) | count(*) | sum(query_time) | min(Date) | Max(Date) |
+--------------------------+----------+-----------------+---------------------+---------------------+
| 5.7233 | 2197 | 12574 | 2008-02-20 22:51:16 | 2008-02-21 17:34:10 |
+--------------------------+----------+-----------------+---------------------+---------------------+
1 row in set (0.09 sec)
优化前:
mysql> select sum(query_time)/count(*),count(*),sum(query_time),min(Date),Max(Date) from slow
where Date>'2008-02-17 22:50:52' and Date<'2008-02-18 17:34:35';
+--------------------------+----------+-----------------+---------------------+---------------------+
| sum(query_time)/count(*) | count(*) | sum(query_time) | min(Date) | Max(Date) |
+--------------------------+----------+-----------------+---------------------+---------------------+
| 2.5983 | 16091 | 41810 | 2008-02-17 22:50:58 | 2008-02-18 17:34:34 |
+--------------------------+----------+-----------------+---------------------+---------------------+
1 row in set (0.15 sec)
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