gl@lbn.fr wrote:
> Hello,
>
> I'm experiencing a strange problem with PostgreSQL 7.4.9.
> One of my database production servers has 2 large databases, it's still
> possible to connect to them and pass queries, but the pg_database
> system table is empty, which prohibits such actions as dumping the
> databases.
I believe that postgresql keeps a plaintext copy of the database table,
because it can't access that table until you are connected.
I'd suggest you make a backup of you whole data directory immediatly, in
case things get worse (e.g. some tries to create a database, and this causes
the plaintext copy to be overwritten).
One reason the pg_database table seems to be empty could be oid wraparound.
Has this database been vacuumed regularly? If not, try doing a "vacuum full"
now - according to some earlier discussion about oid wraparound on this list
this should fix the problem if the wraparound hasn't happend too long ago.
But, in any case, take a (filesystem leven) backup of your database NOW, before
you do anything else.
greetings, Florian Pflug