index.js
function(collectionName, indexName, columns, unique, callback) {

    var options = {
      indexName: indexName,
      columns: columns,
      unique: unique
    };

    return this._run('createIndex', collectionName, options)
      .nodeify(callback);
  }
function(collectionName, indexName, columns, unique, callback) {

    var options = {
      indexName: indexName,
      columns: columns,
      unique: unique
    };

    return this._run('createIndex', collectionName, options)
      .nodeify(callback);
  }
Adds an index to a collection

@param collectionName  - The collection to add the index to
@param indexName       - The name of the index to add
@param columns         - The columns to add an index on
@param	unique          - A boolean whether this creates a unique index