Re: Block-level CRC checks - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Block-level CRC checks
Date
Msg-id 22679.1259704609@sss.pgh.pa.us
Whole thread Raw
In response to Re: Block-level CRC checks  (Bruce Momjian <bruce@momjian.us>)
Responses Re: Block-level CRC checks
List pgsql-hackers
Bruce Momjian <bruce@momjian.us> writes:
> OK, crazy idea #3.  What if we had a per-page counter of the number of
> hint bits set --- that way, we would only consider a CRC check failure
> to be corruption if the count matched the hint bit count on the page.

Seems like rather a large hole in the ability to detect corruption.
In particular, this again assumes that you can accurately locate all
the hint bits in a page whose condition is questionable.  Pick up the
wrong bits, you'll come to the wrong conclusion --- and the default
behavior you propose here is the wrong result.
        regards, tom lane


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