Message-ID: <4C1E537D.5030904@krogh.cc>
Date: Sun, 20 Jun 2010 19:44:29 +0200
From: Jesper Krogh <jesper@krogh.cc>
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To: pgsql-performance@postgresql.org
Subject: Aggressive autovacuuming ?
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Hi.

I have been wondering if anyone has been experimenting with "really 
agressive"
autovacuuming. The database I'm adminstrating rarely have "long running" 
transactions
(over several minutes). And a fair amount of buffercache and an OS cache of
(at best 64GB). A lot of the OS cache is being used for read-caching.

My thought was that if I tuned autovacuum to be "really aggressive" then
I could get autovacuum to actually vacuum the tuples before they
get evicted from the OS cache thus effectively "saving" the IO-overhead
of vacuuming.

The largest consequence I can see at the moment is that when I get a
full vacuum (for preventing transaction-id wraparound) it would be
run with the same aggressive settings, thus giving a real performance
hit in that situation.

Has anyone tried to do similar? What is your experience?
Is the idea totally bogus?

Jesper

-- 
Jesper Krogh