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Re: is pg_autovacuum so effective ?

From: "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>
To: Christopher Browne <cbbrowne(at)ca(dot)afilias(dot)info>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: is pg_autovacuum so effective ?
Date: 2005-02-23 19:18:08
Message-ID: 421CD6F0.8010406@zeut.net (view raw or flat)
Thread:
Lists: pgsql-performance
Christopher Browne wrote:

>Gaetano Mendola <mendola(at)bigfoot(dot)com> writes:
>  
>
>>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.
>  
>

Chris, is this in addition to pg_autovacuum?  Or do you not use 
pg_autovacuum at all?, and if so why not?



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