I keep the same message when trying to dump any database. I haven't a clue; consequently, I'd appreciate any help that you could provide.
postgres(at)ibook:/usr/local/pgsql/bin > ./pg_dump -o discuss -f /tmp/ibook_discuss_db
getDatabase(): SELECT failed. Explanation from backend: 'ERROR: More than one tuple returned by a subselect used as an expression.
'.