public bool MongoClient::close ([ boolean|string
MongoClient::close — Closes this connection
If connection is not given, or
FALSEthen connection that would be selected for writes would be closed. In a single-node configuration, that is then the whole connection, but if you are connected to a replica set, close() will only close the connection to the primary server.
If connection is
TRUEthen all connections as known by the connection manager will be closed. This can include connections that are not referenced in the connection string used to create the object that you are calling close on.
If connection is a string argument, then it will only close the connection identified by this hash. Hashes are identifiers for a connection and can be obtained by calling MongoClient::getConnections().