private int[] createClusters(String className) {
    className = className.toLowerCase();

    final ODatabaseDocumentInternal database = getDatabase();
    final OStorage storage = database.getStorage();

    int[] clusterIds; // CREATE A NEW CLUSTER(S)
    final int minimumClusters = storage.getConfiguration().getMinimumClusters();

    clusterIds = new int[minimumClusters];
    if (minimumClusters <= 1) {
      clusterIds[0] = database.getClusterIdByName(className);
      if (clusterIds[0] == -1) clusterIds[0] = database.addCluster(className);
    } else
      for (int i = 0; i < minimumClusters; ++i) {
        clusterIds[i] = database.getClusterIdByName(className + "_" + i);
        if (clusterIds[i] == -1) clusterIds[i] = database.addCluster(className + "_" + i);
      }
    return clusterIds;
  }
  protected void searchInClusters() {
    final ODatabaseDocumentInternal database = getDatabase();

    final Set<Integer> clusterIds = new HashSet<Integer>();
    for (String clusterName : parsedTarget.getTargetClusters().keySet()) {
      if (clusterName == null || clusterName.length() == 0)
        throw new OCommandExecutionException("No cluster or schema class selected in query");

      database.checkSecurity(
          ORule.ResourceGeneric.CLUSTER, ORole.PERMISSION_READ, clusterName.toLowerCase());

      if (Character.isDigit(clusterName.charAt(0))) {
        // GET THE CLUSTER NUMBER
        for (int clusterId : OStringSerializerHelper.splitIntArray(clusterName)) {
          if (clusterId == -1)
            throw new OCommandExecutionException("Cluster '" + clusterName + "' not found");

          clusterIds.add(clusterId);
        }
      } else {
        // GET THE CLUSTER NUMBER BY THE CLASS NAME
        final int clusterId = database.getClusterIdByName(clusterName.toLowerCase());
        if (clusterId == -1)
          throw new OCommandExecutionException("Cluster '" + clusterName + "' not found");

        clusterIds.add(clusterId);
      }
    }

    // CREATE CLUSTER AS ARRAY OF INT
    final int[] clIds = new int[clusterIds.size()];
    int i = 0;
    for (int c : clusterIds) clIds[i++] = c;

    final ORID[] range = getRange();

    target =
        new ORecordIteratorClusters<ORecord>(database, database, clIds)
            .setRange(range[0], range[1]);
  }