Step through migrations in Rails

tl;dr db:forward is the opposite of db:rollback

bin/rails db:migrate

runs all pending migrations.

If you want to migrate to a specific DB version, you can use 

bin/rails db:migrate VERSION=20190730123456

which is rather cumbersome, especially if you only want to run one migration. Therefore you can use

bin/rails db:forward

You can combine it with variable STEP to execute multiple migrations.

bin/rails db:forward STEP=5