From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-performance@postgresql.org
Subject: Re: Heavy write activity on first vacuum of fresh TOAST data
Date: Thu, 13 Dec 2007 13:52:22 -0500
Message-ID: <17873.1197571942@sss.pgh.pa.us> (raw)
In-Reply-To: <20071213172656.GL6262@alvh.no-ip.org>
References: <4760FF69.EE98.0025.0@wicourts.gov>
<1197562283.4255.1829.camel@ebony.site>
<476108F2.EE98.0025.0@wicourts.gov>
<476108F2.EE98.0025.0@wicourts.gov>
<13267.1197563721@sss.pgh.pa.us>
<47610BF3.EE98.0025.0@wicourts.gov>
<1197565242.4255.1853.camel@ebony.site>
<20071213172656.GL6262@alvh.no-ip.org>
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> Simon Riggs wrote:
>> We might be able to have bgwriter set hint bits on dirty blocks,
> I don't think that works, because the bgwriter has no access to the
> catalogs, therefore it cannot examine the page contents. To bgwriter,
> pages are opaque.
Another issue is that this'd require bgwriter to access the clog SLRU
area. I seem to remember worrying that that could lead to low-level
deadlocks, though I cannot recall the exact case at the moment.
Even without that, it would increase contention for SLRU, which we
probably don't want.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, alvherre@alvh.no-ip.org, simon@2ndquadrant.com, Kevin.Grittner@wicourts.gov
Subject: Re: Heavy write activity on first vacuum of fresh TOAST data
In-Reply-To: <17873.1197571942@sss.pgh.pa.us>
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