From the forum:
"Natively MongoDB allows setting the ReadPreferences and Write Concerns per request. In Hibernate OGM I saw only an option to set this while configuring the MongoDB settings. I don't expect it to be changed frequently, however some parts of our app may potentially use a different read preference/ write concerns. Is there a way to change this dynamically per request without affecting the whole configuration?"

https://forum.hibernate.org/viewtopic.php?f=31&t=1030530