elastic.js/src/aggregations/CardinalityAggregation.js

Javascript API for ElasticSearch DSL

  /**
    @class
    <p>A single-value metrics aggregation that calculates an approximate count of
    distinct values. Values can be extracted either from specific fields in the
    document or generated by a script.</p>

    @name ejs.CardinalityAggregation
    @ejs aggregation
    @borrows ejs.MetricsAggregationMixin.field as field
    @borrows ejs.MetricsAggregationMixin.script as script
    @borrows ejs.MetricsAggregationMixin.lang as lang
    @borrows ejs.MetricsAggregationMixin.params as params
    @borrows ejs.AggregationMixin._type as _type
    @borrows ejs.AggregationMixin.toJSON as toJSON

    @desc
    <p>Aggregation that calculates an approximate count of distinct values.</p>

    @param {String} name The name which be used to refer to this aggregation.

    */
  ejs.CardinalityAggregation = function (name) {

    var
      _common = ejs.MetricsAggregationMixin(name, 'cardinality'),
      agg = _common.toJSON();

    // not supported in cardinality aggregation
    delete _common.scriptValuesSorted;

    return extend(_common, {

      /**
      Set to false to disable rehashing of values.  You must have computed a hash
      on the client-side and stored it into your documents if you disable this.

      @member ejs.CardinalityAggregation
      @param {Boolean} trueFalse set to false to disable rehashing
      @returns {Object} returns <code>this</code> so that calls can be chained.
      */
      rehash: function (trueFalse) {
        if (trueFalse == null) {
          return agg[name].cardinality.rehash;
        }

        agg[name].cardinality.rehash = trueFalse;
        return this;
      },

      /**
      Allows to trade memory for accuracy, and defines a unique count below which
      counts are expected to be close to accurate. Above this value, counts might
      become a bit more fuzzy. The maximum supported value is 40000, thresholds
      above this number will have the same effect as a threshold of 40000.
      Default value depends on the number of parent aggregations that multiple
      create buckets (such as terms or histograms).

      @member ejs.CardinalityAggregation
      @param {Long} num The threshold value
      @returns {Object} returns <code>this</code> so that calls can be chained.
      */
      precisionThreshold: function (num) {
        if (num == null) {
          return agg[name].cardinality.precision_threshold;
        }

        agg[name].cardinality.precision_threshold = num;
        return this;
      }

    });

  };