Elasticsearch: Versioning a document on revisions

I currently have a document which gets revised regularly, I want to keep track of the document by keeping each old version of the document. So if document A has a summary and update date I want to, after every update, keep the previous version along with its update data. The problem is that I'm not sure how I should do this efficiently: ...{ Title: A Summary: {update_date:content, update_date:content, ...} } The problem is that if I take the key as value then the automatic generated schema will take all dates as possible keys. Which is not something you want. So my question is what's the most efficient way of tracking all revisions by date in ElasticSearch?