Re: Acclerating INSERT/UPDATE using UPS

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
Cc: "Bruce Momjian" <bruce(at)momjian(dot)us>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, "Christopher Browne" <cbbrowne(at)acm(dot)org>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Acclerating INSERT/UPDATE using UPS
Date: 2007-02-26 23:11:33
Message-ID: 24176.1172531493@sss.pgh.pa.us
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"Simon Riggs" <simon(at)2ndquadrant(dot)com> writes:
> Reading through the design, I see the following

> - bgwriter performs XLogWrite, not each backend
> - WAL fsync is only performed when WAL file fills
> - no checkpoints are performed until shutdown

> Not checkpointing at all is not a good plan, since this will lead to an
> enormous build up of WAL files and a very long recovery time if the
> system does fail.

Indeed, that seems utterly unacceptable; moreover it's hard to see how
you get a noticeable performance win, compared to a sane checkpoint
interval of some-fraction-of-an-hour.

regards, tom lane

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