Tom Lane wrote:
> 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.
I was assuming any update of hint bits would update the per-page counter
so it would always be accurate. However, I seem to remember we don't
lock the page when updating hint bits, so that wouldn't work.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
