This is a little general I know, but it's been bugging the hell out of me. I've been working on lots of rails projects remotely with Git and every time I do a git pull and see that there is some sort of data change (migration, or schema.rb change) I do a rake db:migrate.

These generally run fine and I can continue working. But if you do a git pull and then git status, your working directory is clean (obviously) then do a rake db:migrate (obviously when there are changes) and another git status and all the sudden your db/schema.rb has changed. I have been just doing a git checkout immediately to reset back to the latest committed version of the schema.rb file, but why should this be necessary?! What is rails doing? Updating a timestamp? I can't seem to figure out what the diff is but maybe I'm just missing something?