i have a materialized view that was created using "ON PREBUILT TABLE" option. right now, i am having problems issuing a complete refresh to the materialized view. the dbms_mview.refresh('materialized_view_1','C') is hanging. i can't drop and recreate the view either because that hangs too. the view is using a source table from another database so it goes through a database link. any ideas on what i need to do?