*** a/src/backend/access/heap/heapam.c
--- b/src/backend/access/heap/heapam.c
***************
*** 5384,5412 **** heap_freeze_tuple(HeapTupleHeader tuple, TransactionId cutoff_xid,
  			TransactionId	update_xid;
  
  			/*
! 			 * This is a multixact which is not marked LOCK_ONLY, but which
! 			 * is newer than the cutoff_multi.  If the update_xid is below the
! 			 * cutoff_xid point, then we can just freeze the Xmax in the
! 			 * tuple, removing it altogether.  This seems simple, but there
! 			 * are several underlying assumptions:
! 			 *
! 			 * 1. A tuple marked by an multixact containing a very old
! 			 * committed update Xid would have been pruned away by vacuum; we
! 			 * wouldn't be freezing this tuple at all.
! 			 *
! 			 * 2. There cannot possibly be any live locking members remaining
! 			 * in the multixact.  This is because if they were alive, the
! 			 * update's Xid would had been considered, via the lockers'
! 			 * snapshot's Xmin, as part the cutoff_xid.
! 			 *
! 			 * 3. We don't create new MultiXacts via MultiXactIdExpand() that
! 			 * include a very old aborted update Xid: in that function we only
! 			 * include update Xids corresponding to transactions that are
! 			 * committed or in-progress.
  			 */
  			update_xid = HeapTupleGetUpdateXid(tuple);
  			if (TransactionIdPrecedes(update_xid, cutoff_xid))
! 				freeze_xmax = true;
  		}
  	}
  	else if (TransactionIdIsNormal(xid) &&
--- 5384,5404 ----
  			TransactionId	update_xid;
  
  			/*
! 			 * This is a multixact which is not marked LOCK_ONLY, but which is
! 			 * newer than the cutoff_multi.  To advance relfrozenxid, we must
! 			 * eliminate any updater XID that falls below cutoff_xid.
! 			 * Affected multixacts may also contain outstanding lockers, which
! 			 * we must preserve.  Forming a new multixact is tempting, but
! 			 * solving it that way requires a WAL format change.  Instead,
! 			 * mark the tuple LOCK_ONLY.  The updater XID is still present,
! 			 * but consuming code will notice LOCK_ONLY and assume it's gone.
  			 */
  			update_xid = HeapTupleGetUpdateXid(tuple);
  			if (TransactionIdPrecedes(update_xid, cutoff_xid))
! 			{
! 				tuple->t_infomask |= HEAP_XMAX_LOCK_ONLY;
! 				changed = true;
! 			}
  		}
  	}
  	else if (TransactionIdIsNormal(xid) &&