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Re: Quick-and-dirty compression for WAL backup blocks

From: Alvaro Herrera <alvherre(at)surnet(dot)cl>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Mark Cave-Ayland <m(dot)cave-ayland(at)webbased(dot)co(dot)uk>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Quick-and-dirty compression for WAL backup blocks
Date: 2005-06-01 14:24:32
Message-ID: 20050601142432.GA23593@surnet.cl (view raw or flat)
Thread:
Lists: pgsql-hackers
On Wed, Jun 01, 2005 at 10:12:34AM -0400, Tom Lane wrote:
> "Mark Cave-Ayland" <m(dot)cave-ayland(at)webbased(dot)co(dot)uk> writes:
> > I also noticed your comment above that mentioned that compression would be
> > less effective as the pages became more full. Would changing the loading
> > factor of database pages have an effect here, as I would have thought that
> > the WAL would be fsync'd more aggressively than the heap?
> 
> Yeah, it's predictable that leaving more free space per page would make
> the optimization more effective.

But it would also increase the number of pages, so maybe there would
have to be block dumps more often, which may make the whole thing worse
on average.

-- 
Alvaro Herrera (<alvherre[a]surnet.cl>)
"La realidad se compone de muchos sueños, todos ellos diferentes,
pero en cierto aspecto, parecidos..." (Yo, hablando de sueños eróticos)

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