如何以频繁的插入率提高MySQL查询的性能？

I'm having approx. 200K rows in a table tb_post, and every 5 minutes it has approx. 10 new inserts.

我有约。表tb_post中有200K行,每5分钟就有一行。 10个新插件。

I'm using following query to fetch the rows -

我正在使用以下查询来获取行 -

SELECT tb_post.ID, tb_post.USER_ID, tb_post.TEXT, tb_post.RATING, tb_post.CREATED_AT,
       tb_user.ID, tb_user.NAME 
FROM tb_post, tb_user 
WHERE tb_post.USER_ID=tb_user.ID 
ORDER BY tb_post.RATING DESC 
LIMIT 30

It's taking more than 10sec to fetch all the rows in sorted fashion.

以分类的方式获取所有行需要10秒以上。

Following is the report of EXPLAIN query:

以下是EXPLAIN查询的报告:

id select_type     table       type    possible_keys   key             key_len     ref         rows        Extra
1   SIMPLE          tb_user     ALL     PRIMARY         NULL            NULL        NULL        20950       Using temporary; Using filesort
1   SIMPLE          tb_post     ref     tb_post_FI_1    tb_post_FI_1    4           tb_user.id  4

Few inputs:

tb_post.RATING is Float type

tb_post.RATING是Float类型

There is index on tb_post.USER_ID

tb_post.USER_ID上有索引

Can anyone suggest me few pointers about how should I optimize this query and improve its read performance?

任何人都可以建议我如何优化此查询并提高其读取性能?

PS: I'm newbie in database scaling issues. So any kinds of suggestions will be useful specific to this query.

PS:我是数据库扩展问题的新手。因此,任何类型的建议都将特定于此查询。

3 个解决方案

#1

You need an index for tb_post that covers both the ORDER BY and WHERE clause.

您需要一个涵盖ORDER BY和WHERE子句的tb_post索引。

CREATE INDEX idx2 on tb_post (rating,user_id)

=> output of EXPLAIN SELECT ...ORDER BY tb_post.RATING DESC LIMIT 30

=> EXPLAIN SELECT的输出... ORDER BY tb_post.RATING DESC LIMIT 30

"id";"select_type";"table";"type";"possible_keys";"key";"key_len";"ref";"rows";"Extra"
"1";"SIMPLE";"tb_post";"index";NULL;"idx2";"10";NULL;"352";""
"1";"SIMPLE";"tb_user";"eq_ref";"PRIMARY";"PRIMARY";"4";"test.tb_post.USER_ID";"1";""

#2

You could try to index tb_post.RATING: MySQL can sometimes use indexes to optimize ORDER BY clauses : http://dev.mysql.com/doc/refman/5.0/en/order-by-optimization.html

您可以尝试索引tb_post.RATING:MySQL有时可以使用索引来优化ORDER BY子句:http://dev.mysql.com/doc/refman/5.0/en/order-by-optimization.html

If you're trying to aggregate data from different tables, you could also check which type of join ( http://en.wikipedia.org/wiki/Join_(SQL) ) you want. Some are better than others, depending on what you want.

如果您尝试聚合来自不同表的数据,您还可以检查所需的连接类型(http://en.wikipedia.org/wiki/Join_(SQL))。有些比其他更好,取决于你想要什么。

#3

What happens if you take the ORDER BY off, does that have a performance impact? If that has a large effect then maybe consider indexing tb_post.RATING.

如果你关闭ORDER BY会发生什么,这会对性能产生影响吗?如果这有很大的影响,那么可以考虑索引tb_post.RATING。

Karl

#1