public static String deltaSubdir(long min, long max) {
    return DELTA_PREFIX + String.format(DELTA_DIGITS, min) + "_" +
        String.format(DELTA_DIGITS, max);
  }
This is format of delta dir name prior to Hive 1.3.x
ql/src/java/org/apache/hadoop/hive/ql/io/AcidUtils.java