rails3 bigint primary key

Question

I would like to create a bigint (or string or whatever that is not int) typed primary key field under Rails 3.

I have a given

Answer 1

skalogirou's answer is good but the change will not be reflected in schema.rb. So the tasks like db:schema:load and db:test:clone will not create identical DB structure.

The required workaround is to enhance db:schema:load and db:test:clone rake tasks as described here: http://www.lshift.net/blog/2013/09/30/changing-the-primary-key-type-in-ruby-on-rails-models/

This is what I used based on that workaround:

namespace :my_app do
  namespace :db do
    task :after_schema_load_and_db_test_clone => :environment do
    puts 'Changing primary key for :my_table'
    query = 'ALTER TABLE  CHANGE id id bigint DEFAULT NULL auto_increment'
    ActiveRecord::Base.connection.execute(query)
  end
end


Rake::Task['db:schema:load'].enhance do
  ::Rake::Task['my_app:db:after_schema_load_and_db_test_clone'].invoke
end

Rake::Task['db:test:clone'].enhance do
  ::Rake::Task['my_app:db:after_schema_load_and_db_test_clone'].invoke
end