I've been noticing quite often lately that the list of Related questions to the right of the screen doesn't always show up, or it takes a while (say, fifteen minutes or more) to do so. Here's an example that (at the moment) has no Related list showing up for me, even though the question is over 5 hours old.

Is the appearance of the Related list a function of the posts views? Or could it be that questions which are not adequately tagged (like the example above with only a [matlab] tag) are hard to create a Related list for?


...and now a Related list just appeared for the sample question I linked to above. I feel a potential [status-norepro] in my future. But it wasn't there before, I swear! The one-armed man must have done it!

  • Well, this post already has a Related list with just 1 view. I guess that answers one of my questions above. Commented Sep 24, 2010 at 18:57
  • Uh oh... the last time this happened was pretty bad... That entirely unrelated incident aside, I've noticed sometimes it won't show up on at first, especially on an immediately asked question. But I've never seen any consistency between when it does and does not show up. To that end, I don't see a Related list on the question you just linked... at least when I first wrote this comment, I didn't see a Related list. Now I do. Wonderful. ♪
    – Grace Note StaffMod
    Commented Sep 24, 2010 at 18:58
  • I see a related list on the example question; is it an intermittent thing? Commented Sep 24, 2010 at 18:58

1 Answer 1


The related query is extremely expensive (500+ms, sometimes up to 2 seconds) so we only do it a certain percentage of the time.

It's also rebuilt periodically on old questions.

  • I guess the question I linked to managed to beat the odds for a few hours then. So does that mean that every time the page is viewed by a user there's some chance that the list will be generated (or regenerated)? Commented Sep 24, 2010 at 19:33
  • @gnos yes, that's right (so long as the related list does not already exist, then the regeneration rules are different) Commented Sep 24, 2010 at 19:35

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