[rt-users] mysqltuner: temp tables & table cache hit rate?

Paul Hirose pthirose at ucdavis.edu
Tue Apr 7 16:50:26 EDT 2009

Since I started RT, I've always gotten these three comments from mysqltuner
[!!] Temporary tables created on disk: 30% (354 on disk / 1K total)
[!!] Table cache hit rate: 18% (40 open / 222 opened)
General recommendations:
     Reduce your SELECT DISTINCT queries without LIMIT clauses

Is there a way to help the above metrics and reduce the select disticnt queries thing?  Are these code-level changes or just more/better usage by our staff?  If it's a usage thing, what things should we stop doing and what should we start doing?

If the answer is to have better/more index in MySQL (a recommendation I've seen many times on this list), could you please also include a recommendation on the index itself?  I don't know what indexes to create.

RT382, MySQL 5.077, Apache 2.2.11, mod-perl 2.04, mysqltuner 1.00, OpenBSD 4.4-STABLE, 2.5GB RAM, 3GB swap.  Machine dedicated to RT.

Thank you,

Paul Hirose          : pthirose at ucdavis.edu : Sysadm Motto: rm -fr /MyLife

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