Executing the stats aggregation

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

Getting ready

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

How to do it...

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

1. We want to calculate all statistical values of a matched query in 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": {}
     },
     "aggs": {
       "age_stats": {
         "extended_stats": {
           "field": "age"
         }
       }
     }
   }'
   

2. The result, if everything is fine, should be:

   {
     "took" : 2,
     "timed_out" : false,
     "_shards" : { …truncated…},
     "hits" : {
       "total" : 1000,
       "max_score" : 0...