[horde] Horde/MySQL problem

[Gottschalk, David]

I apologize in advance if this is not a appropriate question for this list, but I'm really not sure where else to post. Any help would be GREATLY appreciated.

I'm having strange difficulties with my instance of Horde/IMP/Mnemo/Nag and a MySQL database server. My configuration is 2 front-end web servers hosting the Horde setup with a single MySQL back-end database.

Everything runs well, except when I start getting queries like this:

SELECT c.datatree_id, c.datatree_name FROM horde_datatree c LEFT JOIN horde_datatree_attributes a1 ON a1.datatree_id = c.datatree_id LEFT JOIN horde_datatree_attributes a2 ON a2.datatree_id = c.datatree_id WH
ERE c.group_uid = 'horde.shares.mnemo' AND (a1.attribute_name = 'owner' AND a1.attribute_value = 'removed at emory.edu')  AND a2.attribute_name = 'name'  GROUP BY c.datatree_id, c.datatree_name, c.datatree_order
, a2.attribute_value ORDER BY a2.attribute_value ASC;

These queries seem to cause the database to choke when a lot of them come through. Some of them have the group_uid set to horde.shares.nag. I know that Nag and Mnemo use datatree. After a while, MySQL stop responding entirely and it has to be restarted. It appears that this is caused by this types of queries having to be written to tmp disk. I've set my MySQL tmpdir to /dev/shm which is a memory based file system to help improve disk response times.

Anyways, I'm not sure what I can do to improve this. I've already done a ton of MySQL tuning to no avail.

Thanks in advance.

David Gottschalk
UTS Email team
david.gottschalk at emory.edu



This e-mail message (including any attachments) is for the sole use of
the intended recipient(s) and may contain confidential and privileged
information.  If the reader of this message is not the intended
recipient, you are hereby notified that any dissemination, distribution
or copying of this message (including any attachments) is strictly
prohibited.

If you have received this message in error, please contact
the sender by reply e-mail message and destroy all copies of the
original message (including attachments).