anchor.diff:  
   If you come from a SQL background, the above is somewhat similar in concept to the `SQL SELECT FROM` field list.
   
  -Now let's move on to the query part. Previously, we've seen how the `match_all` query is used to match all documents. Let's now introduce a new query called the http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-match-query.html[`match` query], which can be thought of as a basic fielded search query (i.e. a search done against a specific field or set of fields).
  +Now let's move on to the query part. Previously, we've seen how the `match_all` query is used to match all documents. Let's now introduce a new query called the <<query-dsl-match-query,`match` query>>, which can be thought of as a basic fielded search query (i.e. a search done against a specific field or set of fields).
   
   This example returns the account numbered 20:
   
  
positive.code: 
  In the above example, `ctx._source` refers to the current source document that is about to be updated.
  
  Note that as of this writing, updates can only be performed on a single document at a time. In the future, Elasticsearch will provide the ability to update multiple documents given a query condition (like an `SQL UPDATE-WHERE` statement).
  
  === Deleting Documents
  
  
negative.code: 
  Let's start with a basic health check, which we can use to see how our cluster is doing. We'll be using curl to do this but you can use any tool that allows you to make HTTP/REST calls. Let's assume that we are still on the same node where we started Elasticsearch on and open another command shell window.
  
  To check the cluster health, we will be using the <<cat,`_cat` API>>. Remember previously that our node HTTP endpoint is available at port `9200`:
  
  [source,sh]
  --------------------------------------------------
  