rails_db_migration.md

List All Rails Migrations And Their Status

Sometimes, it is nice to know what migrations you have before running them. You can get a list of migrations and their status with:

rake db:migrate:status

Rollback

rake db:rollback STEP=1

Is a way to do this, if the migration you want to rollback is the last one applied. You can substitute 1 for however many migrations you want to go back.

For example:

rake db:rollback STEP=5

Will also rollback all the migration that happened later (4, 3, 2 and also 1).

To roll back all migrations back to (and including) a target migration, use: (This corrected command was added AFTER all the comments pointing out the error in the original post)

rake db:migrate VERSION=20100905201547

In order to rollback ONLY ONE specific migration (OUT OF ORDER) use:

rake db:migrate:down VERSION=20100905201547

Note that this will NOT rollback any interceding migrations -- only the one listed. If that is not what you intended, you can safely run rake db:migrate and it will re-run only that one, skipping any others that were not previously rolled back.

And if you ever want to migrate a single migration out of order, there is also its inverse db:migrate:up:

rake db:migrate:up VERSION=20100905201547

Remove index

For ex: ArgumentError: Index name 'index_responses_on_survey_id_and_survey_template_id' on table 'responses' already exists

ActiveRecord::Migration.remove_index 'responses', name: 'index_responses_on_survey_id_and_survey_template_id'

Re-create test DB

bundle exec rake db:drop RAILS_ENV=test
bundle exec rake db:create RAILS_ENV=test
bundle exec rake db:schema:load RAILS_ENV=test

# Short syntax
bundle exec rake db:drop db:create db:schema:load RAILS_ENV=test