Table locked

[Rafael Pertence Pertence]

I have this table with 17 millions records. I added some indexes and 90% of time it runs very fast.

But sometimes most queries with this table stop returning any data.

The others queries return normally.

I imagined it was a lock problem, so I added this in all my application:

SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;

MY QUERY HERE

SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ;

It didn't solved the problem.


Any ideas?