[horde] Horde Implementation Going South

[Andrew Morgan]

On Wed, 5 Sep 2007, Dave Cunningham wrote:

>
> ok... will try that.
>
> Dave
>
> -----Original Message-----
> From: horde-bounces at lists.horde.org on behalf of Leonardo Rodrigues Magalhães
> Sent: Wed 9/5/2007 1:20 PM
> To: Horde ML
> Subject: Re: [horde] Horde Implementation Going South
>
>
>
> Dave Cunningham escreveu:
>>
>> 2.) MYSQL - We have mysql running on a separate server of the same specs.  It frequently uses 100% of BOTH cpus in what appears, by using myTop, to be a bunch of Join statements on the horde_datatree table. Switching to InnoDB seemed to make it faster at first.  But, as the number of sessions increased, all performance increases were lost and perhaps made worse.  I also tried upgrading mysql from the stock RHEL4 version 4 rpm to the V5 RPM from mysql.org.  There was no noticeable difference there.
>>
>>
>    Are you sure your tables have the needed indexes for your complex
> queries ? I have seen several MySQL falling with high loads and killing
> everything else that depends on it because of some miserable missing
> indexes.
>
>    Try running your queries, in mysql client command line, using
> DESCRIBE before the SELECT .... and watch if mysql is using indexes,
> doing linear scan on the table, etc etc
>
> describe select .... from ... where .....;

Is "DESCRIBE SELECT ..." the same as "EXPLAIN SELECT ..."?

EXPLAIN is the tool I have used to see how MySQL will process a query.

I recommend running ANALYZE TABLE to gather updated statistics on your 
Horde tables.  The table statistics can get stale as your usage ramps up. 
I run the following command nightly:

   mysqlcheck --all-databases --analyze --verbose

If your statistics are stale, MySQL may be doing JOINs inefficiently, 
which is a big part of the datatree usage.


Are you storing sessions in MySQL as well?  The session table can be a 
huge burden on MySQL.  A *lot* of data is stored in the session with Horde 
3.x.  I've moved sessions off into memcache (running on the same server as 
MySQL) and it has been a big performance improvement.


Even still, MySQL is working pretty hard.  I hope the improvements in 
Horde 3.2 will help.

 	Andy