Re: Invalid page header

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Ireneusz Pluta <ipluta(at)wp(dot)pl>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Invalid page header
Date: 2010-09-01 21:36:53
Message-ID: 1688.1283377013@sss.pgh.pa.us
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Ireneusz Pluta <ipluta(at)wp(dot)pl> writes:
> - when playing with pg_filedump I noticed that last pages of the table
> are always initially reported as damaged, as they come, then, as newer
> pages get allocated and filled, these initially bad pages "become
> valid", as in the following example repeating the same pg_filedump.

This doesn't seem terribly surprising. A newly-added page on disk will
be initially filled with zeroes, which I think pg_filedump will complain
about. It won't get overwritten with "valid" data until the page is
next written, either because of a checkpoint or because the buffer space
is needed for another page. pg_filedump can't see the state of the page
within the server's buffers, which is what counts here.

regards, tom lane

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