Planet Flooding

One annoying thing that happens regularly is “Planet Flooding”. This is when one of the many blogs that is syndicated by a public Planet installation changes it’s time stamps and has 10 or more old posts appear as new. It’s doubly annoying when the blogger in question knows about the problem.

Planet Flooding is easy to solve. If you are changing your blogging software or doing something else that may result in old posts appearing to be new then all you have to do is configure your blog to include a small number of posts (maybe two or three) in the RSS feed. Seeing two old posts re-appearing plus a new post explaining it is not going to annoy anyone.

If you run a Planet (or Venus) installation then configure it to have a maximum number of posts per feed. For a Planet that syndicates feeds from a number of individuals and only includes a few days of traffic (which is probably a category that covers most Planets) there is no need for more than four items per feed.

For a severe case of Planet flooding (EG posts which always appear as being the newest and are therefore at the top of the list) the thing to do is to immediately remove the feed until the problem is fixed. Allowing a broken blog configuration to annoy other people is not doing any favors for the blogger in question, it simply drives people to filter the Planet to exclude the articles by that blogger. Yes it does take some work to adjust the configuration of the Planet, but that is surely no more work than replying to email rejecting requests for the configuration to be adjusted.

The first aim of running a blog or a Planet should be to make it readable, Planet flooding breaks this for the Planet and for the blogger who caused it. It is a technical problem and needs a technical solution (which can be temporarily removing the blog from the Planet syndication list).

10 comments to Planet Flooding

  • rob

    I’m a recent culprit of planet flooding, having smacked Planet Linux Australia yesterday. I knew such a thing was possible but short of reading the code (which I don’t have time for) I wouldn’t have known how to avoid it. I was rather surprised that the aggregator didn’t look at the individual post dates and filter out ones older than its already seen.

  • Rob, the whole reason why the posts flood the planet is because the guids of the posts have changed. The aggregator doesn’t seem to care about post dates — it’s the guid that lets the aggregator know that the post is indeed the same post, and it has seen it before.

  • rob

    @Jeremy, thats good to know for next time. Shame I didn’t know beforehand, I could’ve quite easily avoided it.

  • Horms

    The notion of mis-configured feeds breaking planets troubles me. Planets read information from essentialy untrusted sources and thus need to have policies in place to behave sensibly for a wide range of input. We aren’t even talking about malicious attacks here.

  • etbe

    rob: If you merely change the number of posts then you stop it being a problem. No need to read the cost as every blog server has a configuration option for this.

    If that wasn’t an option all that would be necessary in a worst-case scenario is to have a copy of the feed XML file from your old blog be available for a couple of days after installing the new software. That means a couple of days of not creating new posts, but generally after changing software you are too busy fixing things to write new posts for a while.

    Horms: Planet flooding is only the tip of the iceberg. It’s quite simply to configure a Planet to not have this particular problem. Other problems such as unclosed HTML tags are more insidious. I recently dropped a feed from my personal Planet installation because they had an unclosed tag that made the entire rest of my Planet page be a link to their site.

    I’m sure that there are issues with hostile Javascript etc as well.

  • Bravo.
    Any idea on how I can get Planet LA to pay attention to the titles of my WordPress posts (-

  • Jon

    Various Debian packages have patches in them to reduce the number of items in a feed for this reason, details at

  • btmorex

    Post should be renamed: “David Welton, fix your blog”

  • etbe

    Brendan: Try comparing the XML from your blog to the XML from blogs that seem to work correctly.

    btmorex: I was not aiming at anyone in particular. This happens frequently, many people do it.