Java Driver caches index information when using DBCollection.ensureIndex method that makes it unusable if there are multiple apps managing indexing/db.

DBCollection.createIndex on the other hand does not cache this information.

The mongo console does not have the createIndex method, but instead it has ensureIndex.

The behavior of the JS vs Java ensureIndex is expected to be the same.

The caching behavior is not documented anywhere.

In addition, adding this kind of functionality to a db driver does not make sense, as it should serve as a proxy between the applications and the database. The application can decide whether or not to cache such information.