Store in Session Data vs store in Sql Database for temporary data

Question

I am wondering which is more efficient, to store temporary data (related to that session) in a session using the $_SESSION variable in PHP or store and retrieve from an SQL database?

Thank you for your time.

Answer 1

Keep in mind the session variable is backed by a storage mechanism, that is, when the request finishes the session gets written by the session handler, by default this is to a file. On the next request it is pulled back from that file (or whatever else the session handler uses).

If you're reading and writing this data on every request, just stick with a the $_SESSION variables, the overhead of connecting, querying and updating a database will not be faster than the default $_SESSION.

You'll probably only ever want to use a database backed session if you are running multiple load-balanced servers and need to share the session data between them. In this case, if you find the overhead of the database sessions to be slowing down your site to a noticeable degree you might consider sticking memcached between your web server and the database.

Answer 2

I don't know much about reading from a database or a file, but I don't think that "DB access is slower than others" is true. I've learned from my school lessons that Network latency is negligible compared to the I/O access. And if we use DB for sessions, we have some advantages:

We don't have to worried about many servers because there is no file system different.

I also think that storing/reading something to/from a database is more easier than a file system.

Also, if we are using shared hosting, storing sessions in a database is a major advantage for the security.

if i were wrong, please correct me. i still have many things to learn. Thanks.