Justin M Wozniak <jwozniak@cse.nd.edu> writes:
> We noticed that some records were mysteriously disappearing from
> our DB. I went in with psql and found that the \dt command no longer
> works, providing the output below. Is this a sure sign of DB corruption?
> Running psql (PostgreSQL) 7.4.8 on Linux 2.4.27.
> GEMSd=> \dt
> List of relations
> Schema | Name | Type | Owner
> --------+------+------+-------
> (0 rows)
> However... using SELECT statments on tables that I remember are present
> still works...
That sounds like XID wraparound to me --- is it likely that you've
exceeded 2 billion transactions since the tables were created?
If so, a database-wide VACUUM will probably fix it. After which you
should take a hard look at your vacuuming practices.
regards, tom lane