Matt Gray

Feed Overflow

Jan 20, 2010

Today Dez informed me that his RSS reader was chock-full of my old posts. When I launched my new site, a technical difference between the old feed produced by my custom blog software (RSS 1.0) and the feed WordPress generates (RSS 2.0) caused all the posts in my feed to appear as new posts.

Sorry about that!

Why Did This Happen?

Each version of RSS includes an identifier for entries, allowing reader software to tell the difference between new and old content. In RSS 2.0, they are represented by the <guid> tag, while in 1.0 (a different format), they are the rdf:about="" attribute on the <item> tag.

Upgrading to WordPress meant I changed my feed format from RSS 1.0 (RDF) to RSS 2.0. Items in the old feed had IDs like this:
…while in the new feed, IDs are currently:

Oops. Once again, sorry for any hassle. I’d like to change the GUIDs to match my old site, but that might mean deluging RSS subscribers with duplicates if readers don’t handle RSS 1.0 and 2.0 the same way. If you’re wondering (like me) why the versions of RSS are so vastly different, check out the Wikipedia page on RSS.

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