On Tue, 2009-06-09 at 17:28 -0400, Tom Lane wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
> > A corrupt record of a block number would do this in XLogReadBuffer() if
> > we had full page writes enabled. But it would have to be corrupt between
> > setting it correctly and the CRC check on the WAL record. Which is a
> > fairly small window of believability.
>
> > Should there be a sanity check on how far a relation can be extended in
> > recovery?
>
> As you say, that's not a highly believable theory. I'd prefer not to
> put an arbitrary limit into the recovery code unless we can positively
> pin this down as the source of the problem.
>
> Is there any particular reason to suppose that the empty pages appeared
> during a crash recovery?
Probably because my Rorschach tests all look like database recoveries.
> Have you read through md.c? I seem to recall there are some slightly
> squirrelly choices made there about segment-extension behavior. Maybe
> it could've done the wrong thing here during normal operation.
Yes, but will do again if you think I should check.
-- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support
