What is the best and most safest way to handle PHP sessions. Is the best way to store sessions in:
Database (more reliable, but high bottleneck, slow speed, not good for high database usage websites)?
Memcache (super fast, but distributed more security problems, chances of loosing data when the server restarted and chances of loosing data when the cache is full)?
Files (default option, I guess slow since it reads and writes from file I/O, less security, etc).
Which method is the best? What are the problems and good things of each of those approaches?