Enumeration of tables is very slow in largish database

Hi all,

we have a Postgres/PostGIS database with 100+ schemas and 200+ tables in
each schema, generated automatically. When adding a new PostGIS layer in
QGis, the application obviously enumerates all tables, and this takes
minutes. Even browsing the database in pgAdmin3 is horribly slow -- it
takes several seconds to e.g. open a schema (click on a schema's "+" in
the tree view).

The problems occurred only after adding that many schemas to the
database. Before, with only 10+ schemas, the performance was acceptable.

Is this a known limitation of Postgres, or perhaps a misconfiguration of
our installation? What would you suggest to improve performance here? We
currently don't have administration rights for the database or login
rights for the server machine (Linux), but I think we'll need to take
care about that.

Best regards

Kirill