How to speed up single (last) migration test?

Question

I'm writing my migration SQL against tests. Because the migration is the last one and we've got about 300 migrations, it's DAMN SLOW to get there, as it migrates from bottom up every time. Any ideas how to speed this up a bit?

Answer 1

If all your systems are up to date with the latest migration and you don't foresee needing to run any of the previous ones, consider flattening them: you can take the contents of schema.rb and copy it to a new consolidated migration, and delete the 300 old ones.

This might work for you even temporarily while you develop; then restore them when you're done.