I intend to write my own shopping cart and i'm having this problem: for tracking my users should i use sessions in urls or just cookies? Using sessions is the safest way (browsers that don't accept cookies will be "forced" by sessions) but .. starting a new sessions for every new user is a disaster for a seo (no spider will index my files with sessions).
My options:
1) user id and shopping cart entirely in cookies;
2) session id in cookies & shopping cart in DB;
3) session id and shopping cart entirely in sessions;
Any option can be made to be safe but:
1) A few visitors (i think < 5%) don't accept cookies;
2) Using a DB can be nice but a lower number of queries is recommended especially for large eshops.
3) session _id in an internal url is hated by spiders. You may win some potential clients with paranoid privacy settings or prehistoric browsers but you surely lose clients coming from search engines.
So, what would you choose?
Any advice or help would be greatly appreciated.