Executing the global aggregation
Aggregations are generally executed on query search results, ElasticSearch provides a special aggregation—global—that is executed globally on all the documents without being influenced by the query.
Getting ready
You need a working ElasticSearch cluster and an index populated with the script (executing_global_aggregations.sh) available at https://github.com/aparo/elasticsearch-cookbook-second-edition.
How to do it...
To execute global aggregations, we will perform the steps given as follows:
If we want to compare a global average with a query one, the call will be something like this:
curl -XGET 'http://127.0.0.1:9200/test-index/test-type/_search?size=0&pretty=true' -d ' { "query": { "term" : { "tag" : "ullam" } }, "aggregations": { "query_age_avg": { "avg" : { "field" : "age" } }, "all_persons":{ "global": {}, "aggs":{ "age_global_avg": { "avg" : { "field" : "age" ...