Difference between rake db:migrate db:reset and db:schema:load

Question

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.

Answer 1

• 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

• 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.

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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 https://github.com/rails/rails/blob/v3.2.12/activerecord/lib/active_record/railties/databases.rake (for Rails 3.2.x) and https://github.com/rails/rails/blob/v4.0.5/activerecord/lib/active_record/railties/databases.rake (for Rails 4.0.x)