Question

I have been neglecting learning about caching for quite some time now, and although I’ve used caching here and there in the past it’s not something I’m familiar with.

I found a great tutorial about what caching is and what kinds of cache there are (I know already what caching is), but…

How does one decide what and when to cache? Are there things that should always be cached? On what situations should you never use caching?

Answer 1

First rule is: Don’t cache until you need it, that would be premature optimization (first link I found, google for more info)

The biggest problem with caching is invalidation of cache. What happens when the data you have cached is being updated. You need to make sure your cache is updated as well and if not done correctly often becomes a mess.

I would:

1. Build the application without
   caching and make sure the
   functionality works as intended
2. Do some performance testing, and
   apply caching when needed
3. After applying caching do
   performance testing again to check
   that you are getting the expected speed increase