Re: Autovacuum running out of memory

Jason Lustig wrote:
> I lowered the maintenance_work_mem to 50MB and am still getting the same
> errors:
>
> Oct 16 09:26:57 [16402]: [1-1] user=,db= ERROR: out of memory
> Oct 16 09:26:57 [16402]: [1-2] user=,db= DETAIL: Failed on request of
> size 52428798.
> Oct 16 09:27:57 [16421]: [1-1] user=,db= ERROR: out of memory
> Oct 16 09:27:57 [16421]: [1-2] user=,db= DETAIL: Failed on request of
> size 52428798.
> Oct 16 09:29:44 [16500]: [1-1] user=,db= ERROR: out of memory
> Oct 16 09:29:44 [16500]: [1-2] user=,db= DETAIL: Failed on request of
> size 52428798.

Hmm - it's now failing on a request of 50MB, which shows it is in fact
maintenance_work_mem that's the issue.

> Looking at my free memory (from TOP) I find
>
> Mem: 2062364k total, 1846696k used, 215668k free, 223324k buffers
> Swap: 2104496k total, 160k used, 2104336k free, 928216k cached
>
> So I don't think that I'm running out of memory total... it seems like
> it's continually trying to do it. Is there a reason why Postgres would
> be doing something without a username or database? Or is that just how
> autovacuum works?

I've not seen an error at startup before, but if it's not connected yet
then that would make sense.

I'm guessing this is a per-user limit that the postgres user is hitting.
If you "su" to user postgres and run "ulimit -a" that should show you if
you have any limits defined. See "man bash" for more details on ulimit.

--
Richard Huxton
Archonet Ltd