[jarjoura]

This is exactly what Hive is. https://mapr.com/products/apache-hive/

It provides a full SQL query engine on top of unstructured data so you can assemble results.

Personally I would never expose the raw DB in any capacity to the front end systems for security and sanity reasons. DB schemas need to be free to change all the time and you wouldn't want to break entire services from a column type change.