Greg Stark <stark@mit.edu> writes:
>> I think what you're arguing is that we should see WAL records filling the
>> rest of segment 1 before we see any references to segment 2, but if that's
>> the case then how did we get into the situation you reported? Or is it
>> just that it was a broken base backup to start with?
> The scenario I could come up with that didn't require a broken base backup
> was that there was an earlier truncate or vacuum. So the sequence is high
> offset reference, truncate, growth, crash. All possibly on a single
> database.
That's not really an issue, because then it would be OK to discard the
high-offset update; we'd recognize that as safe when we replay the
truncation.
> It's possible we're better off not assuming we've thought of all possible
> ways this can happen though.
That's what's bothering me, too. On the other hand, if we can't think of
a scenario where it'd be necessary to replay the high-offset update, then
I'm disinclined to mess with the code further.
regards, tom lane
