If the user cannot save his shopping cart, the session ID will be fine, just remember that he can change if he starts working through the browser.
If you want the user to be able to store and retrieve the cart, you cannot rely on the session identifier. In this case, you need a user account, and then bind the cart to the user ID.
[EDIT]
, , , .
, - cookie , /.
, , , , , . cookie , . , .
100% , , , .