@HiveDecimalVersionV2
  public boolean isLong() {
    return fastIsLong();
  }
Is the decimal value a long? Range -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
                                   Long.MIN_VALUE                Long.MAX_VALUE
<p>
Emulates testing for no value corruption:
     bigDecimalValue().setScale(0).equals(BigDecimal.valueOf(bigDecimalValue().longValue()))
<p>
NOTE: Fractional digits are ignored in the test since longValue() will
      remove them (round down).
<p>
@return True when longValue() will return a correct long.
storage-api/src/java/org/apache/hadoop/hive/common/type/HiveDecimal.java