Counting

It is often required to return only the count of the matched results and not the results themselves.

There are a lot of scenarios involving counting, some of them are as follows:

• To return a number (for example, how many posts for a blog, how many comments for a post)

• Validating if some items are available: are there posts? are there comments?

Getting ready

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

How to do it...

For executing a counting query, we need to perform the following steps:

1. From command line, we will execute the following count query:

   curl -XGET 'http://127.0.0.1:9200/test-index/test-type/_count' -d '{"match_all":{}}'
   

2. The result returned by ElasticSearch, if everything is all right, should be as follows:

   {
     "count" : 3,
     "_shards" : {
       "total" : 5,
       "successful" : 5,
       "failed" : 0
     }
   }

The result is composed by the count result (a long type) and the shards status at the time of the query.

How it works.....