Cache layer to json api

Rails
1

Hi everyone!

I have a small social website on rails that use react on view and
backend
is just a JSON API,
with more o less 3000 users online at any moment. It runs with
postgres/memcached

When user, for example, visits its feed page, I do:

  1. Select activities from database (20 per page)
  2. Select last 4 comments from each activity from database (justo 1
    select)
  3. Select all users referenced by activity or comment from database
    (select
    users.* from users where id in (1,3,4,5,…100) )

I have a cache layer (memcached) that when I will load users, first I
try
load from memcached, if it not exists I read from database and put it on
cache.
BUT I also have some “listenners” on users model (and over others
referenced models like address and profile) to invalidate cache if any
field change.

The problem:

  • This cache demand a lot of code.
  • Sometimes cache run out of sync.
  • I hate to have this listeners and they are “side effects”

My question is: Any one is doing something like that??
I search A LOT over all google about cache layer to json api and looks
like
that everyone is just using database directly.

I know that Rails has it own solution, but it always end up using
update_at
column, that means, I have to fetch users from database any way.

alternative:

  • Live with date, life is not pretty
  • Buy a more powerful postgres instance… any one is using memcached
    like
    that.
  • Remover listeners, put some expires_in (1 or 2 minutos… or more) and
    let app show out of sync data for a couple of minutes.

thanks for any help!