Noise From My Feeds

Hello, Dear Feed Subscribers,

Let me begin by saying thank you for subscribing to the feed of my website. It is a quiet joy of mine to maintain this little corner of the Web and occasionally spot, in the server logs, that a few of you wander in via your old and trusted feed readers.

Recently, you may have noticed something odd with the feeds from this website. Your feed reader might have shown a bunch of old posts as if they were freshly published. If that happened with your feed reader, I apologise for the noise. I hope this post will give you some clarity on why this happened. The reason for this noise is a change to the way the RSS feeds are generated for this website. Each post in the feeds includes a GUID, which is used by many feed readers to decide whether a post is new or if it has been seen already. Until now, the GUID was simply the post's URL, like this:

<url>https://susam.net/product-of-additive-inverses.html</url>
<guid>https://susam.net/product-of-additive-inverses.html</guid>

However, today this has changed to a randomly generated, permanent short URL, like so:

<url>https://susam.net/product-of-additive-inverses.html</url>
<guid>https://susam.net/p/?cjini</guid>

If your feed reader looks at this GUID value to decide whether a new post has been published, it would show you a whole bunch of old posts once again in your reader, as if they were new. These GUIDs won't change again in the future, so this is a one-time problem only. The full URL of the post is still present in the feeds, as you can see in the example above, so your feed reader still knows where to take you if you wish to visit this website to read a post. The short URL serves only as a unique identifier. However, if someone happens to visit the short URL, it will simply redirect to the full URL.

This website is a passion project I work on in my spare time, and sometimes, after publishing a post, I realise the title could be sharper or the URL could be cleaner. I make the necessary changes and set up HTTP redirects on my web server, so that visitors using the old URL are still taken to the updated location of the post. Previously, however, the GUID (being the URL) changed too, which caused many feed readers to treat the updated post as a new one even when it wasn't. Switching to stable, random GUIDs prevents this problem from occurring again. This website is generated using a small Common Lisp program, so it took just a few quick updates to this program (see commits 4f020eb and c34b9a1) yesterday to implement this change. The GUIDs now stay the same no matter what changes I make behind the scenes, which means no more unnecessary noise in your feed reader.

I am sorry if this caused any confusion or clutter. If your feed reader is currently flooded with old posts appearing as new, the best solution is to mark those items as read. That should restore order and ensure you only see genuinely new posts going forward.

Thanks for your patience, and for continuing to follow along. I promise to keep future surprises limited to content, not configuration.

Cheers,
Your friendly neighbourhood feed fiddler.