Re: More buffers used than a relation's relpages

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Amit Langote <amitlangote09(at)gmail(dot)com>
Cc: Postgres General <pgsql-general(at)postgresql(dot)org>
Subject: Re: More buffers used than a relation's relpages
Date: 2013-06-04 03:17:57
Message-ID: CAMkU=1z6tqC+sfNwXmxR3vXZV4TaXXhnJN1aasoHgpMrUXj7gQ@mail.gmail.com
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On Monday, June 3, 2013, Amit Langote wrote:

> Hello,
>
> In what cases can a relation use more buffers (in shared memory) than
> its pg_class.relpages?
>

I think relpages only counts pages in the main fork, while the buffer cache
will also have buffers for the other forks (visibility map, free space
map). Also, relpages can be out of date if the table has grown since the
last vac/analyze.

Cheers,

Jeff

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