sources said that the aggregate function MAX() has a better performance that select order desc limit 1
有消息称聚合函数MAX()具有更好的性能，可以选择order desc limit 1
but after executing the query from a table with 43000 records, MAX() takes about 1.5 seconds and the other takes 350ms
但是，在从有43000条记录的表执行查询之后，MAX()大约需要1.5秒，另一个需要350ms
and when both are used in inner queries, for about 1 minute MAX() is still executing while the other yield results for 94ms
当在内部查询中同时使用这两种方法时，MAX()仍然在执行大约1分钟，而其他结果为94ms
can anyone enlighten me? I'd really appreciate it
谁能开导我?我真的很感激
1 个解决方案
#1
2
It is all about the INDEXes and the keys that you use. use EXPLAIN to see where your bottlenecks are - http://dev.mysql.com/doc/refman/5.0/en/using-explain.html.
这都是关于你使用的索引和键。使用EXPLAIN查看瓶颈在哪里—http://dev.mysql.com/doc/refman/5.0/en/using-explain.html。
#1
2
It is all about the INDEXes and the keys that you use. use EXPLAIN to see where your bottlenecks are - http://dev.mysql.com/doc/refman/5.0/en/using-explain.html.
这都是关于你使用的索引和键。使用EXPLAIN查看瓶颈在哪里—http://dev.mysql.com/doc/refman/5.0/en/using-explain.html。