CouchDB is a modern key/value-store that has only limited query capabilities (esp. when compared to a typical relational database management system).
All queries are run against materialized views that take only one parameter.
This means that it is very easy to query for documents that were created after a certain point in time, or for ones that were created before, it's not possible to query for documents that have been created between 2 points in time in a single query.
The client application has to issue 2 separate queries and calculate the intersection of a (potentially very large) set of documents itself.