SimplePie: Detecting new feed entries to add to the Database (which is the most efficient way?)

[eluser]richthegeek[/eluser]
md5 the whole feed and store that hash in the database along with the feed URL and ID. the hash will only be 32 characters long, so string comparison isn't a problem, and the feed will remain the same until a new entry is added.

Bear in mind that some RSS feeds just use the current time as the "last updated", so you will need to only hash the entry list, and not rely on the last updated time.