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Re: strange fsm issues

From: Jim Nasby <jnasby(at)pervasive(dot)com>
To: Jeff Frost <jeff(at)frostconsultingllc(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: strange fsm issues
Date: 2006-06-28 00:22:01
Message-ID: 9F858089-CCD2-4F88-BA18-8738ECEF5246@pervasive.com (view raw or flat)
Thread:
Lists: pgsql-admin
On Jun 23, 2006, at 5:31 PM, Jeff Frost wrote:
> On Thu, 22 Jun 2006, Jeff Frost wrote:
>> On Thu, 22 Jun 2006, Jim Nasby wrote:
>>>> CPU 0.00s/0.00u sec elapsed 0.00 sec.
>>>> INFO:  free space map contains 3339998 pages in 125 relations
>>>> DETAIL:  A total of 3341600 page slots are in use (including  
>>>> overhead).
>>>> 3341600 page slots are required to track all free space.
>>>> Current limits are:  3366499 page slots, 2000 relations, using  
>>>> 19853 KB.
>
> So, now after setting it so high and seeing the above output, we  
> ran vacuum verbose again today to check it and it looks like this now:
>
> CPU 0.00s/0.00u sec elapsed 0.00 sec.
> INFO:  free space map contains 27804 pages in 125 relations
> DETAIL:  A total of 29600 page slots are in use (including overhead).
> 29600 page slots are required to track all free space.
> Current limits are:  3366499 page slots, 2000 relations, using  
> 19853 KB.
>
> What the heck?  Why would it have shrunk down so much?  The vacuum  
> full isn't scheduled until tonight. :-/

Take a look at the source for autovacuum... I'm guessing you're right  
and that it doesn't make any special considerations for toast tables,  
which it probably should (since AFAIK you have to first vacuum the  
base table, then commit, then vacuum the toast table).

BTW, tracking pg_class.relpages or actual file size over time would  
probably be helpful.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby(at)pervasive(dot)com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461



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