From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ireneusz Pluta <ipluta@wp.pl>
Cc: pgsql-admin@postgresql.org
Subject: Re: Invalid page header
Date: Wed, 01 Sep 2010 17:36:53 -0400
Message-ID: <1688.1283377013@sss.pgh.pa.us> (raw)
In-Reply-To: <4C7EC335.8060607@wp.pl>
References: <4C7EC335.8060607@wp.pl>
Ireneusz Pluta <ipluta@wp.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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To: pgsql-admin@postgresql.org
Cc: tgl@sss.pgh.pa.us, ipluta@wp.pl
Subject: Re: Invalid page header
In-Reply-To: <1688.1283377013@sss.pgh.pa.us>
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