@HiveDecimalWritableVersionV2
  public static long getDecimal64AbsMax(int precision) {
    return FastHiveDecimalImpl.getDecimal64AbsMax(precision);
  }
See the comments for HiveDecimal.serializationUtilsWrite.
storage-api/src/java/org/apache/hadoop/hive/serde2/io/HiveDecimalWritable.java