Frank van Vugt <ftm(dot)van(dot)vugt(at)foxi(dot)nl> writes:
>> This is the expected case. The failure in CopySnapshot has got to
>> indicate that somebody set one or the other field to some bizarrely
>> large value, though. I take it you didn't run the watchpointed backend
>> far enough to get the memory-alloc error?
> Oh, but I did.....
[ scratches head ... ] AFAICS, the CopySnapshot that gets the error
must be trying to copy one or the other of those snapshots. Maybe you
should look at the address passed to CopySnapshot and see what it's
really pointing at, and where it came from.
regards, tom lane