PHP; use sessions or re-use query?

Question

Hey,

I'm interested in what is the more efficient way of handling user data in my game. When someone is playing the game, data from the server will constantly need to be queried from the database.

So I want to know if it is more efficient to keep querying the database or to store the data from the first query in a session and then keep using the session every time I need the data.

This is probably a stupid question as I think it is going to be sessions that are better, but it's best to be 100% sure :)

Answer 1

If the data will only be updated by the client session in question, then sure, cache it in the session. If other processes will be updating it, then you need to either reobtain it from the database or work out some method for invalidating your session's cached version.

Answer 2

Using sessions will be more efficient. But (assuming the data in the session as cache) any other script not invoked by the user, which updates the dataset you're using, should invalidate the cache somehow.

This means that the cache (now maitained in a session) should be accessible to other scripts. So it might be easier to maintain the cache in files (or you could use php_apc or memcached) instead of sessions.

I think there are many caching classes that are good but the only experience I have is with Zend_Cache and it is really easy to use. It supports APC, memcached, file, etc as backends (a.k.a storage)

Answer 3

Shared state goes in the database, unless you are ready to manage shared access yourself, which is a big pain.

Often-updated user-specific state goes into the session (if you issue an UPDATE every time anyone presses a key in your game, your database is dead).

If you need a superfast session architecture, try memcached.