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Re: Bug (#3484) - Invalid page header again

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Gregory Stark <stark(at)enterprisedb(dot)com>
Cc: "Zdenek Kotala" <Zdenek(dot)Kotala(at)Sun(dot)COM>, pgsql-bugs(at)postgresql(dot)org, "alex" <an(at)clickware(dot)de>
Subject: Re: Bug (#3484) - Invalid page header again
Date: 2007-12-18 19:08:33
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> I don't understand this 9728 bytes. Postgres blocks are 8192 bytes. Are you
> saying one whole block is trashed and then part, but not all, of the next
> block?

> What's the block size of the ZFS filesystem? And what exactly does the trash
> data look like?

It seems relevant that 9728 is a multiple of 512 (and not of any larger
power of 2).  That makes it sound like the misfeasance happened at the
disk block level.  Postgres doesn't internally deal in 512-byte chunks
anywhere I can think of, so to posit a DB bug you have to come up with
some other explanation why exactly that much of the block got trashed.

A filesystem-level software bug is not out of the question, though
this still smells to me like it's a hardware issue of some kind.

			regards, tom lane

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Subject: BUG #3826: Very Slow Execution of examplequery (wrong plan?)
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