Articles in wikipedia get edited. They are able to grow/shrink/up-to-date etc. What file system/database storage layout etc can be used underneath to aid it. In database course, I'd read a little on variable length record, but that appeared like more for small strings and never for whole document. As with file system, files can grow/shrink etc, and i believe its made by chaining blocks together. every time, we update personal files, not the entire file is rewritten. Possibly such like could be done here.

I'm searching for specific names,terminologies, might be even the way the schema in mysql is determined. (I believe wikipedia uses mysql).

Here are links with a writeup on wikipedia architecture, however i am the inability to answer my question from all of these: