Re: is pg_autovacuum so effective ?

Christopher Browne wrote:
> Gaetano Mendola <mendola@bigfoot.com> writes:
>
>
>>Tom Lane wrote:
>>
>>>Gaetano Mendola <mendola@bigfoot.com> writes:
>>>
>>>
>>>>I'm using ony pg_autovacuum. I expect that disk usage will reach
>>>>a steady state but is not. PG engine: 7.4.5
>>>
>>>
>>>One data point doesn't prove that you're not at a steady state.
>>
>>I do a graph about my disk usage and it's a ramp since one week,
>>I'll continue to wait in order to see if it will decrease.
>>I was expecting the steady state at something like 4 GB
>>( after a full vacuum and reindex ) + 10 % = 4.4 GB
>>I'm at 4.6 GB and increasing. I'll see how it will continue.
>
>
> You probably want for the "experiment" to last more than a week.
>
> After all, it might actually be that with your usage patterns, that
> table would stabilize at 15% "overhead," and that might take a couple
> or three weeks.
>
> Unless it's clear that it's growing perilously quickly, just leave it
> alone so that there's actually some possibility of reaching an
> equilibrium.  Any time you "VACUUM FULL" it, that _destroys_ any
> experimental results or any noticeable patterns, and it guarantees
> that you'll see "seemingly perilous growth" for a while.
>
> And if the table is _TRULY_ growing "perilously quickly," then it is
> likely that you should add in some scheduled vacuums on the table.
> Not VACUUM FULLs; just plain VACUUMs.
>
> I revised cron scripts yet again today to do hourly and "4x/day"
> vacuums of certain tables in some of our systems where we know they
> need the attention.  I didn't schedule any VACUUM FULLs; it's
> unnecessary, and would lead directly to system outages, which is
> totally unacceptable.

Yes, I'm in this direction too.


Regards
Gaetano Mendola