How to store field data in a file instead of the db? So far, I found two decent options for storing field in a file:


using node hooks to store data in a filefield, and process it on node view
theoretically, the best would be to use file storage as a backend, but is there a module for field file storage instead of field sql storage? 


My use case is a field that does not change, but mysql backup is very slow because there are 600 000 nodes with it. I also do not need to query this field, just display it. With file storage I can do incremental backup which is lightyears more efficient.
Your best bet's going to be using the MongoDB module, I think ... Here is a quote about it (from the module's project page):

... is a collection of several modules which allow sites to store different types of Drupal data in MongoDB.
Views integration provided by EntityFieldQuery Views Backend.