Re: Detecting corrupted pages earlier

Tom Lane wrote:
> Andrew Sullivan <andrew(at)libertyrms(dot)info> writes:
> > You know you have big-trouble, oh-no, ISP ran over
> > the tapes while they were busy pitching magnets through your cage,
> > data corruption problems, and this is your best hope for recovery?
> > Great. Log in, turn on this option, and start working. But across
> > every back end? It's the doomsday device for databases.
>
> Yeah, it is. Actually, the big problem with it in my mind is this
> scenario: you get a page-header-corrupted error on page X, you
> investigate and decide there's no hope for page X, so you turn on
> zero_damaged_pages and try to dump the table. It comes to page X,
> complains, zeroes it, proceeds, ... and then comes to damaged page Y,
> complains, zeroes it, proceeds. Maybe you didn't know page Y had
> problems. Maybe you could have gotten something useful out of page Y
> if you'd looked first. Too late now.
>
> What I'd really prefer to see is not a ZERO_DAMAGED_PAGES setting,
> but an explicit command to "DESTROY PAGE n OF TABLE foo". That would
> make you manually admit defeat for each individual page before it'd
> drop data. But I don't presently have time to implement such a command
> (any volunteers out there?). Also, I could see where try-to-dump, fail,
> DESTROY, try again, lather, rinse, repeat, could get pretty tedious on a
> badly damaged table.

Can we make the GUC setting a numeric, so you can set it to 1 and it
clears just one page, or 0 and it clears all pages?

--
Bruce Momjian | http://candle.pha.pa.us
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