- 话题 - 文江博客

发布于 2024-12-02 16:24:50 字数 378 浏览 1 评论 0原文

This query is against a MyISAM table:

SELECT * FROM table 
           WHERE link_id = 1 and counted = 1

Now, if I don't pass counted, it gets it really fast. When I pass counted to it, it just takes forever. It is a big table, but I don't see the reason why it should get stuck instead of just showing me an empty table.

有什么想法吗？

原文

This query is against a MyISAM table:

SELECT * FROM table 
           WHERE link_id = 1 and counted = 1

Any ideas?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

往事随风而去 2024-12-09 16:24:50

EXPLAIN SELECT * FROM table WHERE link_id = 1 and counted = 1

Run this to see if you're table has proper indexes. Perhaps counted does not have an index?

EXPLAIN SELECT * FROM table WHERE link_id = 1 and counted = 1

回复收藏 0 原文

无声静候 2024-12-09 16:24:50

(link_id, counted) 上的索引将使查询速度更快。

回复收藏 0 原文

过潦 2024-12-09 16:24:50

这是因为它必须过滤每一行的 counted=1 。您是否在 link_id 上设置了索引？如果是这样，您可以设置一个计数

回复收藏 0 原文

机场等船 2024-12-09 16:24:50

我的猜测是你只是缺少一个索引。试试这个：

SHOW INDEXES FROM <your table name>

您是否在 column_name 字段中看到 counted ？

如果没有，那么您可能想要：

CREATE INDEX <nifty index name> ON <your table name> (counted);

接下来我会看看 EXPLAIN （Micah 解释了此处）。（我只建议解释第二个，因为我的经验是，大多数情况下，如果查询很慢，问题只是缺少索引。）

My guess is that you are simply missing an index. Try this:

SHOW INDEXES FROM <your table name>

Do you see counted in the column_name field?

If not, then you probably want to:

CREATE INDEX <nifty index name> ON <your table name> (counted);

I would next look to EXPLAIN (which Micah explains here). (I only suggest explain second because my experience is that the majority of the time the problem is simply a missing index if a query is slow.)

回复收藏 0 原文

~没有更多了~