title: Elasticsearch query for what fields have a given type?
body: <p>I have an elasticsearch (version 1.7) cluster with multiple indices. Each index has multiple doc_types, and each has fields w/ a variety of types. I'd like to get a list of field names for a given field type. This would be a necessarily nested list. For example, I'd like to query for field type "string", and return {index1: {doc_type1.1: [field1.1.1, field1.1.2], ...} -- the leaves of this nested dicts are only those fields w/ the given type. So the hits for this query won't be documents but rather a subset of the cluster's mapping. Is this possible using Elasticsearch? </p>
  
  <p>One solution: I know I can get the mapping as a dict using Python, then work on the mapping dict to recover this nested list. But I think there should be an elasticsearch way of doing this, not a Python solution. In my searches through the documentation I just keep finding the "type filter" which filters by doc_type, not field type. </p>