Question

I am in the process of creating a Facebook App for my website which includes functionality that requires the users friends list.

Retrieving the friends is no problem, what I am struggling to decide, is how to store them.

1. Option 1 – Store the users in my MySQL database, I have opted not to go for this as my database will become very heavy, very quickly. In addition, I will need to create a table for each individual Facebook user!
2. Option 2 – Store the Facebook friends array in a session which is updated every half an hour to ensure new friends are included. Ignore the fact that the session updates every half an hour, is it a bad idea to store, what can be a very large array, within a session?

The website is likely to be receiving high volumes of traffic, and will therefore be storing a lot of these sessions.

Although I am an experienced developer, I am not overly experienced with sessions in these circumstances. I would simply like to know whether or not this is a bad idea?

Just to give you a little info on the typical friends array:

1. Each array is multidimensional in the format {0[uid:1,name:Jo Bloggs,picture:test.jpg],1…}
2. A friends list typically ranges from 100 items to 5000 items, although averaging around 700. These are not small!

If this is a bad method for storing the friends, what other options (excluding MySQL) are there?

Do sessions have an effect on memory (RAM) usage?

Answer 1

For your requirements, I highly recommend installing MemCacheD on your server. See: http://memcached.org/ for more information.

Session is only for the current user logged in, so sharing the information would be hard between sessions. Also when the session goes away, so does the user data.

For memcached data is stored in key/value pairs.

So for a key, you could use facebook ID, and for the value, a serialized object of user data.