private static String generateTmpPath(StorageDescriptor sd) {
    return sd.getLocation() + "/" + TMPDIR + "_" + UUID.randomUUID().toString();
  }
Generate a random tmp path, under the provided storage.
@param sd storage descriptor, must be not null.
@return path, always not null
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/MRCompactor.java