[OSM-talk] Problem Solved WAS: Re: Server slowness

[Nick Hill]

The problem we have been experiencing seems to be caused by large numbers of RSS 
feed queries.

An RSS feed query covers a 0.4x0.4 degree tile. Extracts all nodes, sorts them, 
then takes the top 40. These are then keyed against the users table. Naturally, 
the users table is locked whilst the query is performed. This made it look like 
a users table problem.

Since I disabled RSS at midnight, the database load has dropped by at least 80%.

http://www.openstreetmap.org/munin/openstreetmap/db.openstreetmap-cpu.html

Nick Hill wrote:
> I have been pouring over the SQL passing through Mysql today. Queries which seem 
> to be taking ages peel off top 40 nodes with user IDs. I guess these are RSS 
> feed queries.
> 
> I have therefore just broken the RSS system in the apache conf of www to check 
> this is the culprit.