Shopping Cart - Store in sessions?
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I'm developing a shopping cart for a website, and was wondering what way should I store the product id after the user has clicked on the "Add to cart".

Should I store them in a session -- Such as 

    $_SESSION['cart'][$productid]++;

Would this put strain on the server under load? Or is this the best way of doing it?

Or should I create a temp database table, store the information in there, and remove after order has been processed?

