PHP + MySQL + Feeds

[Supremacy]

Hey,

 

Im working on a blog website, but one problem Im having is figuring out how to import user's existing blog entries. I know I must parse feeds etc, but my problem is this:

 

When I parse a feed for the first time, it must insert the entries into my database, thats all good. But now comes the problem of importing after that. How do I differentiate between content I have already stored in my database and new entries on the feed that have been posted since my last import?

 

I cant clear out my database each time, as there will be multiple feeds from multiple users and each entry would have its own comments, so dropping all entries from a feed would mean I loose the comments too. I thought of using the post date of each entry on the feed to determine whether I have the entry or not, but Im not sure its the best idea. Entries from major blogging systems such as Wordpress etc. dont have a unique identifier for each post do they?

 

Thanks

Justin