Jonathan Foy <thefoy@gmail.com> writes:
> My vacuums have suddenly started to fail, seemingly at random. I am
> confused.
> I'm running 8.1.3, with close to a dozen servers, up to 150 databases each.
> I have 8GB of RAM. Vacuums have started to fail on all servers (though only
> the occasional vacuum) with the following error:
> VACUUM,ERROR: out of memory
> VACUUM,DETAIL: Failed on request of size 268435452
I'd back off maintenance_work_mem if I were you. I think you don't have
enough RAM to be running a lot of concurrent VACUUMs all with the same
large memory consumption.
Also, if it's really 8.1.3, consider an update to 8.1.something-recent.
Not only are you exposed to a number of very serious known bugs, but
this patch in particular would likely help you:
http://archives.postgresql.org/pgsql-committers/2007-09/msg00377.php
regards, tom lane