can't drop an old tablespace

Hello,

(Postgres 8.3, Linux)

while trying to drop a tablespace, I get an error tablespace "xxx" is
not empty.

There are effectively a few files within the corresponding folder,

but all of them are empty and a few months old.

moreover, pg_class does not contain any references to this tablespace.

What should I do to safely get rid of this tablespace:

- Is there a way to obtains all dependent objects of a tablespace ?

- How is this error triggered ? comes it from a check of the folder
content, or from the catalog ?

many thanks,

Marc Mamin