According to one embodiment of the present invention, a system extends a content repository by creating an auxiliary data store outside of the content repository and storing auxiliary data in the auxiliary data store, wherein the auxiliary data is associated with a collection of documents in the content repository. The system stores version information for the auxiliary data store and records of operations against the auxiliary data store in a log in the repository. In response to receiving a request for an operation against the auxiliary data store, the system determines that the auxiliary data store and repository are consistent based on the version information and applies the operation against the auxiliary data store. Embodiments of the present invention further include a method and computer program product for extending a content repository data model in substantially the same manners described above.