This kind of aggregation allows executing analytics on nested documents. When working with complex structures, the nested objects are very common.
You need an up-and-running Elasticsearch installation, as we described in the Downloading and installing Elasticsearch recipe in Chapter 2, Downloading and Setup.
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 script (
chapter_08/populate_aggregations.sh) available in the online code.
For executing nested aggregations, we will perform the following steps: