How-To handle AutoExpiring Shopping Carts

I'm currently developping a online shopping store and the question of expiring carts comes.

Should i use event based self timed cart entity, or should i make kind of polling task to cleanup o开发者_JS百科ld empty carts ?

Thanks

---

I would use self timed cart entity and simply doesn't show expired carts. For db sanity, I would also make daily or weekly (depends on traffic You have) cleaning procedure which will remove all expired carts... but on the other hands You can use this data for analysis (what-customers-want) so in this case, preserve or compact.