@Test
  public void testMapRedPlan6() throws Exception {

    LOG.info("Beginning testMapPlan6");
    populateMapRedPlan6(db.getTable(Warehouse.DEFAULT_DATABASE_NAME,
        "src"));
    executePlan();
    fileDiff("lt100.sorted.txt", "mapredplan6.out");
  }
test reduce with multiple tagged inputs.
ql/src/test/org/apache/hadoop/hive/ql/exec/TestExecDriver.java