Moshe Jacobson <moshe@neadwerx.com> writes:
> Yesterday I found that one of the databases in my database cluster suddenly
> lost all its tables. A \dt in psql showed nothing. I'm not sure how or when
> it happened, but it was either due to an upgrade of postgres from 9.1 to
> 9.3 or else something going wrong with pg_dump.
This sounds like a transaction ID wraparound issue, ie, the pg_class rows
are still there but you can't see them because they're "in the future".
VACUUM FREEZE would probably fix it, but the interesting question is why
didn't the built-in wraparound defenses prevent this from happening.
Could we see the output from pg_controldata?
regards, tom lane