vlv-search/db/migrate.rb

require 'sequel'

def migrate
  db = Sequel.connect(adapter: :postgres, database: 'vlv2')

  db.create_table :threads do
    primary_key :id
    String :title
    String :creator, index: true
    Integer :remote_id, index: true, unique: true
    String :last_post_creator
    DateTime :last_post_created_at
    DateTime :created_at, index: true
  end

  db.create_table :posts do
    primary_key :id
    String :body
    String :creator, index: true
    Integer :remote_id, index: true, unique: true
    foreign_key :thread_id, :threads
    DateTime :created_at, index: true
  end

  db.create_function(:update_last_post, <<-SQL, language: :plpgsql, returns: :trigger)
    BEGIN
      UPDATE threads
      SET
        last_post_created_at = NEW.created_at,
        last_post_creator = NEW.creator
      WHERE
        threads.id = NEW.thread_id;
      RETURN NEW;
    END
  SQL

  db.run(<<-SQL)
    CREATE TRIGGER update_last_post
    AFTER INSERT ON posts
    FOR EACH ROW
    EXECUTE PROCEDURE update_last_post();
  SQL
end