Kevin Kempter <cs_dba(at)consistentstate(dot)com> writes:
> we have a few not null constraints we want to drop on very large tables.
> Unfortunately the drop's are taking hours. Is there a way to drop a not null
> constraint via the system catalogs?
Dropping a NOT NULL constraint is a trivial operation. The problem is
probably that you are blocked waiting to get a lock on the table.
Look for idle-in-transaction sessions that are holding locks on the
target table.
regards, tom lane