Relay: How To Get Connection From Store When Used With Order_by Or Other Params?

I have a question regarding ConnectionHandler used in updater. I am reading the example and found

import {ConnectionHandler} from 'relay-runtime';

// The `friends` connection record can be accessed with:
const user = store.get(userID);
const friends = RelayConnectionHandler.getConnection(
 user,                        // parent record
 'FriendsFragment_friends'    // connection key
 {orderby: 'firstname'}       // 'filters' that is used to identify the connection
);
// Access fields on the connection:
const edges = friends.getLinkedRecords('edges');

So the connections could accept {orderby: 'firstname'}. What is my orderby field can take in either firstname or secondname or fullname? So if I am sorting by firstname, I should update the connection with orderby = firstname and when I am sorting by lastname, I should get connection by orderby = lastname ... How do I know which orderby I am under or could I just update the "current one"?

@Junchao, I see that you took this example from the relay docs right? This orderby that is passed, you are not actually telling Relay to order the edges for you by firstname, but this parameter is the filters one, which is used to identify the connection like said on the comment. If you specified a filter on your query, you also must pass the filter on getConnection, otherwise, you won't find it.

:)