[Kushfield]

Changing the data on a MySQL database can be just as easy, if not easier than changing it on a file. You just need to use a tool like phpMyAdmin or HeidiSQL for easy management of the database. Although it might be a bit of a hassle at first, in the long run you will definitely be glad to have switched to a proper database system for storing your data.

I can only think of one option that might help you delay the switch, although still not ideal. You could try loading all the users from the file into a Trie with names as the keys on map change. Then do a lookup for the name in the Trie when players connect instead of directly in the file. On registration, you would have to insert the new data in both places.