MongoCursorInterface::setReadPreference

The read preference mode: MongoClient::RP_PRIMARY, MongoClient::RP_PRIMARY_PREFERRED, MongoClient::RP_SECONDARY, MongoClient::RP_SECONDARY_PREFERRED, or MongoClient::RP_NEAREST.

An array of zero or more tag sets, where each tag set is itself an array of criteria used to match tags on replica set members.

Returns this cursor.

Emits E_WARNING if either parameter is invalid, or if one or more tag sets are provided with the MongoClient::RP_PRIMARY read preference mode.

read preferences -

MongoCursorInterface::getReadPreference() -