Ruby-on-rails – Difference between rake db:migrate db:reset and db:schema:load


The difference between rake db:migrate and rake db:reset is pretty clear in my head. The thing which I don't understand is how rake db:schema:load different from the former two.

Just to be sure that I am on the same page:

  • rake db:migrate – Runs the migrations which haven't been run yet.
  • rake db:reset – Clears the database (presumably does a rake db:drop + rake db:create + rake db:migrate) and runs migration on a fresh database.

Please help to clarify, if my understanding has gone wrong.

Best Solution

  • db:migrate runs (single) migrations that have not run yet.

  • db:create creates the database

  • db:drop deletes the database

  • db:schema:load creates tables and columns within the existing database following schema.rb. This will delete existing data.

  • db:setup does db:create, db:schema:load, db:seed

  • db:reset does db:drop, db:setup

  • db:migrate:reset does db:drop, db:create, db:migrate

Typically, you would use db:migrate after having made changes to the schema via new migration files (this makes sense only if there is already data in the database). db:schema:load is used when you setup a new instance of your app.

I hope that helps.

UPDATE for rails 3.2.12:

I just checked the source and the dependencies are like this now:

  • db:create creates the database for the current env

  • db:create:all creates the databases for all envs

  • db:drop drops the database for the current env

  • db:drop:all drops the databases for all envs

  • db:migrate runs migrations for the current env that have not run yet

  • db:migrate:up runs one specific migration

  • db:migrate:down rolls back one specific migration

  • db:migrate:status shows current migration status

  • db:rollback rolls back the last migration

  • db:forward advances the current schema version to the next one

  • db:seed (only) runs the db/seed.rb file

  • db:schema:load loads the schema into the current env's database

  • db:schema:dump dumps the current env's schema (and seems to create the db as well)

  • db:setup runs db:schema:load, db:seed

  • db:reset runs db:drop db:setup

  • db:migrate:redo runs (db:migrate:down db:migrate:up) or (db:rollback db:migrate) depending on the specified migration

  • db:migrate:reset runs db:drop db:create db:migrate

For further information please have a look at (for Rails 3.2.x) and (for Rails 4.0.x)