I'd like to suggest extending the note in the docs on orm.joined load with something like the following: [http://docs.sqlalchemy.org/en/latest/orm/loading_relationships.html#sqlalchemy.orm.joinedload, http://docs.sqlalchemy.org/en/rel_0_8/orm/loading.html#sqlalchemy.orm.joinedload]
If you have already explicitly JOINed a collection onto your query for filtering (or other use), you will likely want to use
orm.contains_eager instead of
joinedload will create a second anonymously aliased join, while
contains_eager will more efficiently re-use the existing join.