Why does schema.rb change (in the eyes of Git) when just running rake db:migrate?!

Question

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?

Answer 1

schema.rb reflects your database schema so when you migrate(with changes) it follow that your schema also changes to reflect your db change. I usually add schema.rb to our gitignore, along with database.yml (probably because instead of using schema:load like the one below, i usually do a sql dump when cloning an existing app - but that's just me)

Answer 2

The schema enables machines to run rake db:schema:load when being setup for the first time instead of having to run the migrations, which can go out of date if models are renamed or removed, etc. It's supposed to update after a migration, and you always want to latest version checked into source control.

Answer 3

The end of db:migrate is to dump the schema. It will have different timestamps (git should tell you), and different versions of rails/database gems will give you slightly different formats. It's a minor annoyance to see this all the time.

I recommend you add schema.rb to your .gitignore file.