ProjectionMap loadaProjectionMap = loada.getProjectionMap();
assertTrue(loadaProjectionMap.changes() == false);
LOLoad loadb = (LOLoad) lp.getRoots().get(1);
ProjectionMap loadbProjectionMap = loadb.getProjectionMap();
assertTrue(loadbProjectionMap.changes() == false);
//check frjoin projection map
LOJoin frjoin = (LOJoin)lp.getSuccessors(loada).get(0);
ProjectionMap frjoinProjectionMap = frjoin.getProjectionMap();
assertTrue(frjoinProjectionMap != null);