Google Feedfetcher and Distinct feed-id Values

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Posted on December 09, 2007 12:37 PM in Web Development
Warning: This blog entry was written two or more years ago. Therefore, it may contain broken links, out-dated or misleading content, or information that is just plain wrong. Please read on with caution.

It's a little unfortunate that you can't really count on a single Google Feedfetcher ping of your feed in your referrer log to determine the total count of subscribers using Google properties.

I must say, though, that it is nice how they provide a concise explanation of a very deterministic approach to finding out what the total count is:

The "User-Agent:" header of our crawler includes the name of our crawler ("FeedFetcher-Google") along with its associated URL, the subscriber count, and a unique 64-bit feed identifier ("feed-id"). You might see multiple requests for the same feed with distinct "feed-id" values. This happens if the same feed is referenced through multiple URLs (for example, because of redirects). In that case, you'll need to sum up the subscribers to a feed that have distinct "feed-id" values to determine the total number of Google subscribers to the feed.

From my experience looking at pings from other crawlers like Bloglines', I don't believe they take the same approach, so from time-to-time you may see a very low subscriber count followed by a higher one, depending on whether a redirect occurred or a different URI was used to subscribe (the latter provides an excellent reason to use unambiguous URIs).


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