@Test
  public void testDecimalColMultiplyDecimalColumn() throws HiveException {
    VectorizedRowBatch b = getVectorizedRowBatch3DecimalCols();
    VectorExpression expr = new DecimalColMultiplyDecimalColumn(0, 1, 2);
    DecimalColumnVector r = (DecimalColumnVector) b.cols[2];

    // test without nulls
    expr.evaluate(b);
    assertTrue(r.vector[0].getHiveDecimal().equals(HiveDecimal.create("1.20")));
    assertTrue(r.vector[1].getHiveDecimal().equals(HiveDecimal.create("-3.30")));
    assertTrue(r.vector[2].getHiveDecimal().equals(HiveDecimal.create("0.00")));

    // test that underflow produces NULL
    b = getVectorizedRowBatch3DecimalCols();
    DecimalColumnVector c0 = (DecimalColumnVector) b.cols[0];
    c0.vector[0].set(HiveDecimal.create("9999999999999999.99")); // set to max possible value
    DecimalColumnVector c1 = (DecimalColumnVector) b.cols[1];
    c1.vector[0].set(HiveDecimal.create("2.00"));
    r = (DecimalColumnVector) b.cols[2];
    expr.evaluate(b); // will cause overflow for result at position 0, must yield NULL
    assertTrue(!r.noNulls && r.isNull[0]);
  }
Unit tests for vectorized arithmetic expressions.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/expressions/TestVectorArithmeticExpressions.java