Before the deeper evaluation we simply made a table of pros and cons of all the different databases. Below are what we considered the pros and cons of CouchDB for our use case.

Pros:

  * Projection feature
     address “weird” Ansible data format requirements.
     allow for a more compact and logical structure to be presented to the api.
  * Built in support for compaction
  * Built-in versioning

Cons:

  * couchdb versioning may not align with our notion of versioning
  * Requires a lot of space
  * Views instead of arbitrary queries
  * Performance not so predictable. (see how reads trigger version logic) (Colleague has had experience with this problem)

Edit: I found some other notes ...

    CouchDB appears to be a strong candidate. I am worried about the space requirements/consumptions. CouchDB uses views of data rather than queries.

Database comparison by feature matrix: http://i.imgur.com/6bdIvwE.png