Question

I have a query that takes about a minute to complete since it deals with a lot of data, but I also want to put the results on a website. The obvious conclusion is to cache it (right?) but the data changes as time goes by and I need a way to automatically remake the cached page maybe every 24 hours.

can someone point me to how to do this?

edit: I want to make a “top 10” type of thing so it’s not displaying the page that is the problem but the amount of time it takes for the query to run.

Answer 1

Caching the results of the query with a 24hr TTL (expiry) would probably work fine. Use a fragment cache assuming this is a chunk of the page.

You can setup memcached or redis as stated to store the cache. Another thing you can do is setup a job that warms the cache every 24 hrs (or as desired) so that unlucky user doesn’t have to generate the cache for you.

If you know when the cache is expired base on a state or change in your database you can expire the cache based on that. A lot of times I use the created at or updated at fields as part of the cache key to assist in this process.

There is some good stuff in the scaling rails screencasts by envy labs and new relic. http://railslab.newrelic.com/scaling-rails, a little out of date but the principles are still the same.

Also, checkout the caching rails guides. http://guides.rubyonrails.org/caching_with_rails.html

Finally, make sure indexes are setup properly, use thoughtbots post here: http://robots.thoughtbot.com/post/163627511/a-grand-piano-for-your-violin

Typed on my phone so apologies for typos.