Executing the top hit aggregation

The top hit aggregation is different from the other aggregation types. All the previous aggregations have metric (simple values) or bucket values; the top hit aggregation returns buckets of search hits.

Generally, the top hit aggregation is used as a subaggregation so that the top matching documents can be aggregated in buckets.

Getting ready

You need a working ElasticSearch cluster and an index populated with the script (chapter_06/executing_top_hit_aggregations.sh) available at https://github.com/aparo/elasticsearch-cookbook-second-edition.

How to do it...

To execute a top hit aggregation, we will perform the steps given as follows:

1. We want to aggregate the documents hits by tag (tags) and return only the name field of documents with a maximum age (top_tag_hits). We'll execute the search and aggregation with the following command:

   curl -XGET 'http://127.0.0.1:9200/test-index/test-type/_search' -d '{
     "query": {
       "match_all...