> 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.
It's possible we're better off not assuming we've thought of all possible
ways this can happen though.