public static String deltaSubdir(long min, long max, int statementId) {
    return deltaSubdir(min, max) + "_" + String.format(STATEMENT_DIGITS, statementId);
  }
Each write statement in a transaction creates its own delta dir.
@since 1.3.x
ql/src/java/org/apache/hadoop/hive/ql/io/AcidUtils.java