title: Keep session in koa on multiple servers
body: <p>I have multiple koa servers with a load balancer, using passport login. I would like to keep the session across all servers. </p>
  
  <p>My first attempt was to set the session storage to be in mysql database, but this caused the server to call mysql on each request, thus causing performance issues.  </p>
  
  <p>I would like to keep the session object in the RAM of each server, and if the user gets redirected to another server by the load balancer and the server doesn't recognize the cookie, I would like it to fallback to a database and load the data into its RAM too.<br>
  Is there a way to do this?  </p>
  
  <p>Thanks.</p>