Possible DB corruption

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

On Fri, May 25, 2007 at 04:47:52PM -0400, Justin M Wozniak wrote:

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.

You might be suffering from transaction ID wraparound. Are you
vacuuming regularly?

http://www.postgresql.org/docs/7.4/interactive/maintenance.html#VACUUM-FOR-WRAPAROUND

"...every table in the database must be vacuumed at least once every
billion transactions."

--
Michael Fuhr

On Mon, May 28, 2007 at 04:14:14PM -0600, Michael Fuhr wrote:

On Fri, May 25, 2007 at 04:47:52PM -0400, Justin M Wozniak wrote:

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.

You might be suffering from transaction ID wraparound.

Another possibility: has search_path changed? You said that \dt
shows nothing but you can still query the tables -- do you use
schema-qualified table names in those queries?

--
Michael Fuhr