@Test
  public void testMultiKeyIntStringString() throws HiveException {
    testMultiKey(
        "sum",
        new FakeVectorRowBatchFromObjectIterables(
            2,
            new String[] {"int", "string", "string", "double"},
            Arrays.asList(new Object[]{null,   1,  1, null,    2,    2, null}),
            Arrays.asList(new Object[]{ "A", "A", "A", "C", null, null,  "A"}),
            Arrays.asList(new Object[]{ "A", "A", "A", "C", null, null,  "A"}),
            Arrays.asList(new Object[]{ 1.0, 1.0,  1.0, 1.0, 1.0,  1.0,  1.0})),
        buildHashMap(
            Arrays.asList(   2, null, null), 2.0,
            Arrays.asList(null,  "C",  "C"), 1.0,
            Arrays.asList(   1,  "A",  "A"), 2.0,
            Arrays.asList(null,  "A",  "A"), 2.0));
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java