@Override
    public String partitionDescToString() {
      StringBuilder sb = new StringBuilder();
      for (String partDesc : partitionDesc) {
        String[] partition = CacheTag.decodePartDesc(partDesc);
        sb.append(partition[0]).append('=').append(partition[1]);
        sb.append('/');
      }
      sb.deleteCharAt(sb.length() - 1);
      return sb.toString();
    }
CacheTag for tables with more than one partition level.
storage-api/src/java/org/apache/hadoop/hive/common/io/CacheTag.java