title: How to make elasticsearch add the timestamp field to every document in all indices?
body: <p>Elasticsearch experts,</p>
  
  <p>I have been unable to find a simple way to just tell ElasticSearch to insert the _timestamp field for all the documents that are added in all the indices (and all document types). </p>
  
  <p>I see an example for specific types:
  <a href="http://www.elasticsearch.org/guide/reference/mapping/timestamp-field/" rel="noreferrer">http://www.elasticsearch.org/guide/reference/mapping/timestamp-field/</a></p>
  
  <p>and also see an example for all indices for a specific type (using _all):
  <a href="http://www.elasticsearch.org/guide/reference/api/admin-indices-put-mapping/" rel="noreferrer">http://www.elasticsearch.org/guide/reference/api/admin-indices-put-mapping/</a></p>
  
  <p>but I am unable to find any documentation on adding it by default for all documents that get added irrespective of the index and type.</p>