mongoc_read_concern_t

The mongoc_read_concern_t allows clients to choose a level of isolation for their reads. The default, MONGOC_READ_CONCERN_LEVEL_LOCAL, is right for the great majority of applications.

You can specify a read concern on connection objects, database objects, or collection objects.

See readConcern on the MongoDB website for more information.

Read Concern is only sent to MongoDB when it has explicitly been set by mongoc_read_concern_set_level to anything other then empty string.

See Read Concern Levels in the MongoDB manual for more information about the individual read concern levels.