Executing filter/query facets

Sometimes, we don't need complex computation, but only the number of hits that verifies a particular query or filter. To obtain this result, the filter/query facet is used.

Getting ready

You need a working ElasticSearch cluster and an index populated with the script available in the online code.

How to do it...

For executing filter/query facets, we will perform the steps given as follows:

1. We need to compute two different filter facets, which are:

   • The count of documents that have "ullam" as tag

   • The count of documents that have age equal to 37

2. The query to execute these facets is:

   curl -XGET 'http://127.0.0.1:9200/test-index/test-type/_search?from=0&pretty=true&size=0' -d '
   {
       "query": {
           "match_all": {}
       },
       "facets": {
           "ullam_docs": {
               "filter" : {
                 "term" : { "tag" : "ullam" }
   }
           },
           "age37_docs": {
               "filter" : {
                 "term" : { "age" : 37 }
   }
           }
       }
   }'

   In this case we...