public static BucketIdentifier from(Configuration conf, Path path) {
    if (!AcidUtils.isInsertOnlyFetchBucketId(conf)) {
      return null;
    }

    return BucketIdentifier.parsePath(path);
  }
Stores bucket and writeId of the bucket files.
ql/src/java/org/apache/hadoop/hive/ql/io/BucketIdentifier.java