DRILL-5496: Fix for failed Hive connection If the Hive server restarts, Drill either hangs or continually reports errors when retrieving schemas. The problem is that the Hive plugin tries to handle connection failures, but does not do so correctly for the secure connection case. The problem is complex, see DRILL-5496 for details.
This is a workaround: we discard the entire Hive schema cache when we encounter an unhandled connection exception, then we rebuild a new one.
This is not a proper fix; for that we'd have to restructure the code.
This will, however, solve the immediate problem until we do the needed restructuring.