I was playing around on SEDE when I noticed some questions have a favourite count of 0, while the majority have a favourite count of NULL. What's the reason behind this? For the questions with a count of 0, did somebody add it as a favourite in the past and removed it later (possibly even when their account was removed)? Looking at this answer, it might very well be the case.

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This behaviour seems to happen on all sites in the network, not just Meta. I've already checked migrations as a possible cause, but nope. Here are two queries to view more examples:

A related issue is Why do some comments have 0 score but others have null score in Data Explorer?. While this behaviour makes writing some niche queries slightly more complex than needed, it's far from being a bug and this question is also to satisfy my curiosity.

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  • @Rob the first one definitely not; ViewCount cannot be NULL under any circumstances (you can't unview a question) and views aren't stored per user. The second one could arguably be expanded into including an answer to this question, but I doubt it's useful (though I'm going to mark some columns as nullable since they apparently are).
    – Glorfindel Mod
    May 4, 2019 at 7:25
  • I believe that the duplicate explains how that occurs, perhaps it's technical for some (Catija didn't get my comment to her answer, so I deleted it and placed my comment onto the other post that you linked to in your question). I don't think it's technical for you. I don't have access behind the curtain - you say "under any circumstances" - so what if a Dev nukes a post and then restores it, they might overwrite the view count because it serves no purpose; while they might keep the text for legal purposes. 2nd scenerio: Post is submitted and the view count isn't incremented, it's NULL.
    – Rob
    May 4, 2019 at 8:59
  • Here is one explanation (possibly not current) of how views are counted. As you can see, if the page isn't loaded (such as after the submit button is pressed) or the cache is lost the count isn't incremented from its initialization value (or subsequent higher value). I'd still like to look for a newer explanation of the working, as time permits, if SE offers an explanation.
    – Rob
    May 4, 2019 at 9:27

1 Answer 1


From looking at a few examples in each list, it seems that 0 indicates a question that has been favorited at some point but the favorite was removed. Questions in the NULL list have never been favorited.

This seems like an interesting thing to know. If no one has ever found it interesting, that's kinda different than someone thinking it's worth favoriting for some reason and then deciding later to purge it from their list of favorites. The info isn't particularly useful as it could have been favorited for many reasons:

  • accidentally
  • to remind oneself to bounty it
  • to remind oneself to answer it or look at it later to see if its answered.
  • to check in and see if it's edited or clarified.

There are dozens of potential reasons for this but it's still kinda interesting to know.


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