Text indexes have a default language_override of "language". Users can change this to point to a different field, but there is no mechanism to disable it entirely (and, specifying a language_override of "" is equivalent to not specifying the option at all). language_override should accept a value that disables it entirely.

This would allow users to disable the stemmer in a schema-independent way (to achieve this currently, users have to set language_override to some field that will never be present in any of the collection's documents).