如何提示要在MySQL选择查询中使用的索引?
我有一个MySQL查询(正在运行MySQL 5.0.88),我正在尝试加快该查询的速度.基础表具有多个索引,并且对于所查询的查询,使用了错误的索引(i_active
-16.000行,而i_iln
-7行).
I have a MySQL query (running MySQL 5.0.88), which I'm trying to speed up. The underlying table has multiple indices and for the query in question, the wrong index is used (i_active
- 16.000 rows, vs. i_iln
- 7 rows).
我对MySQL不太熟悉,但是读到有一个use index
提示,它可以迫使mySQL使用某个索引.我正在这样尝试:
I'm not very experienced with MySQL but read there is a use index
hint, which can force mySQL to use a certain index. I'm trying it like this:
SELECT art.firma USE INDEX (i_iln)
...
但这会产生MySQL错误.
but this produces a MySQL error.
问题:
谁能告诉我我在做什么错? (除了运行5.0.88,我无法更改.)
Question:
Can anyone tell me what I'm doing wrong? (Except running 5.0.88, which I can't change.)
您错过了
FROM table
正确的SQL应该是:
SELECT art.firma FROM your_table USE INDEX (i_iln) WHERE ....