Re: Subtraction carry bug in xlog.c in 7.3 and 7.4

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От Tom Lane
Тема Re: Subtraction carry bug in xlog.c in 7.3 and 7.4
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Msg-id 17802.1056118498@sss.pgh.pa.us
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Ответ на Subtraction carry bug in xlog.c in 7.3 and 7.4  ("J.R. Nield" <jrnield@usol.com>)
Ответы Re: Subtraction carry bug in xlog.c in 7.3 and 7.4  (Bruce Momjian <pgman@candle.pha.pa.us>)
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"J.R. Nield" <jrnield@usol.com> writes:
> The attached patches against 7.3 and 7.4 fix a subtraction carry bug in
> xlog.c.

This is simply a waste of cycles, because xrecoff can never be zero
(if it were, it'd be pointing at a page header, which is not a valid
record location).  If you look around in the code, you'll note that
xrecoff==0 is actually used as an invalid-value flag in a couple of
contexts.

Can you point to anyplace where the behavior would change?  If so
I think there's a deeper bug to fix.

            regards, tom lane

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