Re: Experimental patch for inter-page delay in VACUUM

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Neil Conway <neilc(at)samurai(dot)com>
Cc: Jan Wieck <JanWieck(at)yahoo(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Ang Chin Han <angch(at)bytecraft(dot)com(dot)my>, Christopher Browne <cbbrowne(at)acm(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Experimental patch for inter-page delay in VACUUM
Date: 2003-11-10 20:36:36
Message-ID: 200311102036.hAAKaaX06203@candle.pha.pa.us
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Neil Conway wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Another idea --- if fsync() is slow because it can't find the dirty
> > buffers, use write() to write the buffers, copy the buffer to local
> > memory, mark it as clean, then open the file with O_SYNC and write
> > it again.
>
> Yuck.

This idea if mine will not even work unless others are prevented from
writing that data block while I am fsync'ing from local memory --- what
if someone modified and wrote that block before my block did its fsync
write? I would overwrite their new data. It was just a crazy idea.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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