Aggregations take the results of a query and group the data into logical sets. Aggregations can be composed to provide complex data summaries.

Liferay DXP 7.2 has a new API that exposes Elasticsearch’s native Aggregation functionality.

Currently, these aggregation types are supported:

  • Bucketing aggregations create buckets of documents based on some criterion. They support sub-aggregations.

    • Supported bucket aggregations include children aggregations, date histogram aggregations, date range aggregations, diversified sampler aggregations, filter aggregations, filters aggregations, geo distance aggregations, geo hash grid aggregations, global aggregations, histogram aggregations, missing aggregations, nested aggregations, range aggregations, reverse nested aggregations, sample aggregations, significant terms aggregations, significant text aggregations, and terms aggregations.
  • Metrics aggregations compute metrics over a set of documents.

    • Supported metrics aggregations include average aggregations, cardinality aggregations, extended stats aggregations, geo bounds aggregations, geo centroid aggregations, max aggregations, min aggregations, percentile ranks aggregations, percentiles aggregations, scripted metric aggregations, stats aggregations, sum aggregations, top hits aggregations, value count aggregations, and weighted average aggregations.
  • Pipeline aggregations aggregate the output of other aggregations and their associated metrics.

    • Supported pipeline aggregations include average bucket pipeline aggregations, bucket metrics pipeline aggregations, bucket script pipeline aggregations, bucket selector pipeline aggregations, bucket sort pipeline aggregations, cumulative sum pipeline aggregations, derivative pipeline aggregations, extended stats bucket pipeline aggregations, max bucket pipeline aggregations, min bucket pipeline aggregations, moving function pipeline aggregations, percentiles bucket pipeline aggregations, pipeline aggregations, serial diff pipeline aggregations, stats bucket pipeline aggregations, and sum bucket pipeline aggregations.

All the supported aggregations are found in the portal-search-api module’s package.

In addition to these aggregations, other aggregation-like features are present in the Liferay DXP search API:

Group By collects search results (documents) based on a particular field. For example, if you want to group the search results based on the asset type (e.g., web content article, document, blog post, etc.), you can create a search query that contains a aggregation with the field entryClassName.

You can specify these attributes for returned groups:

  • The maximum number of results in each group
  • Special sorting for the grouped results

Facets act like bucket aggregations, holding results that share a certain characteristic.

Using Aggregations

The generalized approach for using aggregations in your own search code is like this:

  1. Instantiate and construct the aggregation object
  2. Add the aggregation information to the search request
  3. Process the search response

These steps are covered in more detail (with examples) here.

External References

Search Engine Connector Support

  • Elasticsearch 6: Yes
  • Solr 7: No

New/Related APIs

API (FQCN)Provided by ArtifactNotes
« Introduction to SearchCreating Aggregations »
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