Curt Sampson <[EMAIL PROTECTED]> writes:
> On Mon, 17 Feb 2003, Tom Lane wrote:
>> Postgres has a bad habit of becoming very confused if the page header of
>> a page on disk has become corrupted.
> What typically causes this corruption?
Well, I'd like to know that too. I have seen some cases that were
identified as hardware problems (disk wrote data to wrong sector, RAM
dropped some bits, etc). I'm not convinced that that's the whole story,
but I have nothing to chew on that could lead to identifying a software
bug.
> If it's any kind of a serious problem, maybe it would be worth keeping
> a CRC of the header at the end of the page somewhere.
See past discussions about keeping CRCs of page contents. Ultimately
I think it's a significant expenditure of CPU for very marginal returns
--- the layers underneath us are supposed to keep their own CRCs or
other cross-checks, and a very substantial chunk of the problem seems
to be bad RAM, against which occasional software CRC checks aren't
especially useful.
regards, tom lane
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