[ADMIN] About System Catalogs

[Francesco . Borgoglio]

Hi gurus,
i have two questions for you.

1) I would like to know if the system catalogs tables are created
     for each database of Postgresql instance or belong to a specific db, such as template0 i suppose.

2) As i had a very large pg_largeogject, i deleted rows e now i have a clean, small table.
    The table is empty but its index  pg_largeogject_loid_pn_index  lasts to retain a lot of bytes.
     How can i do?
     I have to drop and recreate the index?

Thank you very much.