How to hint the index to use in a MySQL select query?

Question

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).

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)
 ...

but this produces a MySQL error.

Question:
Can anyone tell me what I'm doing wrong? (Except running 5.0.88, which I can't change.)

Answer 1

You missed the FROM table

Correct SQL should be:

SELECT art.firma FROM your_table USE INDEX (i_iln) WHERE ....

Answer 2

select * from table use index (idx);

http://dev.mysql.com/doc/refman/5.0/en/index-hints.html

Answer 3

sometimes, with use index (index_name) optimizer might go for table scan, if you use hint force index, optimizer will be forced to use index, will go for table scan only if no ways left to get the rows with provided index.

SELECT art.firma FROM art FORCE INDEX (i_iln);

for more detail on hints USE INDEX and FORCE INDEX check this link

Answer 4

Select Coloumn1,Coloumn2,Coloumn.... FROM TABLE_NAME USE INDEX(index_name) WHERE Coloumn="condition";

if you have correct index thn you dnt need to use index(). your query automic select correct index.If your query slow after using index thn recheck your index ,something wrong in index. thanks in advance.enter code here