That seems like it would totally break the model, where you subscribe to sub-Reddits you want to read and don't subscribe to ones you don't want to read.
As written it would, but you could trivially adapt it to the subreddit level. Cache each subreddit the same way, then coalesce the results dynamically, which would still remove the main bottleneck of connecting to the db.
So we are keeping thousands of subreddits cached that then get dynamically composed together to determine an individual users front page? How did we just not create a second database?
I'm basically advocating for a system similar to Erlang Term Storage (ETS) but for those who don't use Erlang. Given that rewriting reddit in Erlang/Elixir would be unpalatable we can take the lessons from how other systems maintain high availability and apply them to our environment.
