gistfile1.rb

def listen_thread(url)
  listen_conn = DriverManager.get_connection(url)
  
  stmt = listen_conn.create_statement
  stmt.execute("LISTEN watchers")
  stmt.close

  while true
    sleep 1
    puts 'polling...'

    notifications = listen_conn.get_notifications || []

    notifications.each do |notification|
      unless notification.nil?
        puts "NOTIFICATION ------------"
        puts "pid: #{notification.pid}" 
        puts "name: #{notification.name}"
        puts "param: #{notification.parameter}"
        puts "-------------------------"

        id = notification.parameter.split(',').last
        puts "RETRIEVING RECORD FOR NOTIFIED ID: #{id}"
        stmt = listen_conn.create_statement
        rs = stmt.execute_query("SELECT * FROM watched_table WHERE id = #{id}")

        while rs.next
          puts "id:\t#{rs.get_int(1)}"
          puts "value:\t#{rs.get_int(2)}"
          puts "record_time:\t#{rs.get_timestamp(3)}"
        end

        puts "-------------------------"

        stmt.close
        rs.close
      end
    end
  end
end