  1) First, we lock DWP_MERGE_E242F5DA52.target_events in TD_MAP1 for
     write on a reserved RowHash to prevent global deadlock.
  2) Next, we lock DWP_MERGE_E242F5DA52.target_events in TD_MAP1 for
     write.
  3) We do an INSERT step into Spool 2.
  4) We do a single-AMP RETRIEVE step from Spool 2 (Last Use) by way of
     an all-rows scan into Spool 1 (used to materialize view, derived
     table, table function or table operator s) (all_amps), which is
     redistributed by the hash code of (:? (INTEGER)) to all AMPs in
     TD_MAP1.  Then we do a SORT to order Spool 1 by row hash.  The
     size of Spool 1 is estimated with high confidence to be 1 row (29
     bytes).  The estimated time for this step is 0.00 seconds.
  5) We do an all-AMPs merge with unmatched inserts into
     DWP_MERGE_E242F5DA52.target_events from Spool 1 (Last Use) with a
     condition of ("DWP_MERGE_E242F5DA52.target_events.event_id =
     EVENT_ID").  The number of rows merged is estimated with high
     confidence to be 1 row.  The estimated time for this step is 1.61
     seconds.
  6) Finally, we send out an END TRANSACTION step to all AMPs involved
     in processing the request.
  -> No rows are returned to the user as the result of statement 1.