Elasticsearch experts,
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).
I see an example for specific types: http://www.elasticsearch.org/guide/reference/mapping/timestamp-field/
and also see an example for all indices for a specific type (using _all): http://www.elasticsearch.org/guide/reference/api/admin-indices-put-mapping/
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.
Elasticsearch used to support automatically adding timestamps to documents being indexed, but deprecated this feature in 2.0.0
From the version 5.5 documentation:
The _timestamp and _ttl fields were deprecated and are now removed. As a replacement for _timestamp, you should populate a regular date field with the current timestamp on application side.