Session VS File VS Memcache for a Cache in PHP?

Question

I have a social network

• The users table is around 60,000 rows

• The friends table is around 1 million rows (used to determine who is your
  

Answer 1

The default maximum object size that is allowed in Memcache is 1MB.

@jsaondavis : "session data is saved into a file".

Your above statement is wrong. Session can be configured to store in database. Default session hadndler is file.