Which option is more scalable?

Question

I'm working on php, mysql on a project

I'm planning to add a multilanguage option, usually I use single textfile for each php file, but I want to know if one of the followings is good or not and why.

• Using one single textfile for the whole site: This would make my life peacefully because I have to make changes in one place only, but I don't know how scalable this option would be.
• Using xml files for each php, is this scalable for dictionaries?
• Using one single xml file, is this scalable for dictionaries?
• Using a table in the db, I used this options a few times, but I read that it make the webpage slower and is not really scalable

That are my options, if any have a better one I would be greatfully, and if anyone have an advice on the pseudocode (I usually use a big array) and a replacement Welcome too :D

Answer 1

I only use db when I need other people to add / modify datas in my translation.

Else I use a php file by language, defining my variables in each.

Answer 2

use gettext
wordpress is a good example if you need one

as for your question, separate language files is the only solution, letting many people work on different languages separately