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 sub-aggregation, so that the top matching documents can be aggregated in buckets.
You need an up-and-running Elasticsearch installation, as we described in the Downloading and installing Elasticsearch recipe in Chapter 2, Downloading and Setup.
To execute curl via the command line, you need to install curl for your operative system.
To correctly execute the following command, you need an index populated with the chapter_08/populate_aggregations.sh script available in the online code.
