Using 128bit UUIDs with ActiveRecord

create_jobs.rb

class CreateJobs < ActiveRecord::Migration
  def up
    create_table :jobs do |t|
      t.timestamps
    end

    sql = <<-SQL
    ALTER TABLE "jobs" ALTER COLUMN id DROP DEFAULT,
        ALTER COLUMN id TYPE uuid USING uuid_generate_v4(),
        ALTER COLUMN id SET DEFAULT uuid_generate_v4();
    DROP SEQUENCE "jobs_id_seq";
    SQL
    execute sql

    add_index :jobs, :id
  end

  def down
    remove_index :jobs, :id
    drop_table :jobs
  end
end

setup_postgres_exts.rb

class SetupPostgresExts < ActiveRecord::Migration
  def self.up
    sql = <<-SQL
CREATE EXTENSION IF NOT EXISTS hstore;
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
CREATE EXTENSION IF NOT EXISTS plpgsql;
    SQL

    execute sql
  end

  def self.down
    execute "DROP EXTENSION hstore"
    execute "DROP EXTENSION \"uuid-ossp\""
    execute "DROP EXTENSION plpgsql"
  end
end