CODEWITHSUNDEEP
ruby-on-rails-3cachingmemcached
Geo
Geo

Reputation: 96897

Rails 3 cache questions

Say I want to use the dalli store for caching (fragments of) views. Does this mean that doing something like this will also use memcache for possible DB caching?

Rails.cache.fetch("something") { smth }

Also, if I do something like:

Author.all

the Rails console will show me that it's querying the database, but if I run Author.all again, it will show me that the results are retrieved from cache. When do I want to explicitly use Rails.cache and when should I rely on ActiveRecord to do the caching?

Upvotes: 0

Views: 731

Answers (1)

0x4a6f4672
0x4a6f4672

Reputation: 28245

Fetch and read operations get items from the cache store which is currently configured, for example from the file system if the cache store is :file_store, or from the Memcached server if the store is :mem_cache_store. Therefore if you want to use Memcached for fragment caching, you have to configure the cache_store accordingly:

ActionController::Base.cache_store = :mem_cache_store, "cache-1.example.com"

It is recommendable to use fragment caching if one has large, complex views involving many queries which change rarely or slowly. Fragement caching is a good trade-off between completely static pages (fast, but fixed) and dynamic pages (slow, but variable). If you need to cache a certain section of a page instead of the entire page, fragment caching is the way to go, as Ryan Bates said in his Railscast about fragment caching.

Page and action caching are even better, they are great for speeding up the performance of a page, but problematic if it contains user-specific content. In this case it is possible to use dynamic page caching. Stackoverflow uses a similar technique.

SQL Caching persists only for the duration of a single action.

Upvotes: 1

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