The edX modulestore stores the course content for all versions of all courses and is backed by MongoDB.
http://edx.readthedocs.io/projects/edx-developer-guide/en/latest/modulestores/index.html
...
The edX modulestore stores the course content for all versions of all courses and is backed by MongoDB.
http://edx.readthedocs.io/projects/edx-developer-guide/en/latest/modulestores/index.html
...