Hi,

Your questions are answered in the manual:
http://dev.mysql.com/doc/refman/5.0/...cache-how.html

It is a known limitation.

Edoardo Serra wrote:
> Hi all,
> I'm benchmarking performance improvement with MySQL Query Cache
> turned on but I'm facing some problem with queries inside stored
> procedures when they contains variable parameters
>
> I just created this stored procedure to identify the problem
>
> CREATE PROCEDURE `proc_test_qcache`(IN mailbox_number VARCHAR(64)) READS
> SQL DATA DETERMINISTIC
> BEGIN
> SELECT password FROM users WHERE mailbox = mailbox_number;
> END
>
> I see, looking at Qcache status, that calls to that stored procedure
> are not cached.
>
> Is it a known limitation ?
>
> I think that MySQL should evaluate caching after variable substitution
> but I'm not aware of MySQL internals to judge if this is the correct
> behaviour.
>
> P.S: I noticed that MySQL caches without problems queries contained in
> stored procedures which does not contains variables.
>
> Tnx in advance for
>
> Regards
>
> Edoardo Serra
> WeBRainstorm S.r.l.
>