public static String nameFromOffset(final long offset, final String fileSuffix) {
        final NumberFormat nf = NumberFormat.getInstance();
        nf.setMinimumIntegerDigits(20);
        nf.setMaximumFractionDigits(0);
        nf.setGroupingUsed(false);
        return nf.format(offset) + fileSuffix;
    }
Storage util. Used for data and index file storage format.
inlong-tubemq/tubemq-server/src/main/java/org/apache/inlong/tubemq/server/broker/utils/DataStoreUtils.java