Executing stats aggregations

The most commonly used metric aggregations are stats aggregations. They are generally used as a terminal aggregation step to compute values to be used directly or for sorting.

Getting ready

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.

How to do it...

For executing a stat aggregation, we will perform the following steps:

1. We want to calculate all statistics values of a matched query on the age field. The REST call should be as follows:

           curl -XPOST "http://127.0.0.1:9200/test-index/_search?
           size=0" -d ' 
           { 
               "query": { 
                   "match_all": {} 
     ...