Re: Vacuum, visibility maps and SKIP_PAGES_THRESHOLD

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Vacuum, visibility maps and SKIP_PAGES_THRESHOLD
Date: 2011-06-06 07:39:56
Message-ID: 4DEC844C.5030107@enterprisedb.com
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On 03.06.2011 22:16, Bruce Momjian wrote:
> I realize we just read the pages from the kernel to maintain sequential
> I/O, but do we actually read the contents of the page if we know it
> doesn't need vacuuming?

Yes.

> If so, do we need to?

Not necessarily, but it allows us to freeze old tuples, and doesn't cost
much anyway.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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