"Victor Yegorov" <viy(at)pirmabanka(dot)lv> writes:
> May be I'll put my question in a different manner:
> System tables are location-wide (I mean one set of tables for PostgreSQL
> location) or each database has it's own set of system tables?
pg_database, pg_shadow, pg_group are shared, the rest are per-database.
These three are generally not so large that it's worth worrying about
vacuuming them extra times ...
regards, tom lane