title: What should be stored in cache for web app?
body: <p>I realize that this might be a vague question the bequests a vague answer, but I'm in need of some real world examples, thoughts, &amp;/or best practices for caching data for a web app.  All of the examples I've read are more technical in nature (how to add or remove cache data from the respective cache store), but I've not been able to find a higher level strategy for caching.</p>
  
  <p>For example, my web app has an inbox/mail feature for each user.  What I've been doing to date is storing typical session data in the cache.  In this example, when the user logs in I go to the database and retrieve the user's mail messages and store them in cache.  I'm beginning to wonder if I should just maintain a copy of all users' messages in the cache, all the time, and just retrieve them from cache when needed, instead of loading from the database upon login.  I have a bunch of other data that's loaded on login (product catalogs and related entities) and login is starting to slow down.</p>
  
  <p>So I guess my question to the community, is what would you do/recommend as an approach in this scenario?</p>
  
  <p>Thanks.</p>