Suppose I created a table table in a Rails app. Some time later, I add a column running:
rails generate migration AddUser_idColumnToTable user_id:string.
Then I realize I need to add user_id as an index. I know about the add_index method, but where should this method be called? Am I supposed to run a migration (if yes, which one ?), then adding by hand this method?
This question is related to
ruby-on-rails
indexing
migration
You can run another migration, just for the index:
class AddIndexToTable < ActiveRecord::Migration
def change
add_index :table, :user_id
end
end