This fall I will be migrating to a much newer version of Elasticsearch (from 1.5.2). This will be done by setting up a new server to be used by my application and then following this, bulk loading the data from the many (3 per month) indexes to the new system.
My question is this: if I set up the new system with an updated template for the indexes (with new fields), how will Elasticsearch handle older index documents that are missing the new fields?