Some questions on Stack Exchange sites get deleted, but they are still linked from various other places on the internet. I will use this deleted question from Mathematics Stack Exchange as an example.1 If the deleted question was a duplicate, it might be useful for people who followed a link to that question to see at least the duplicate target.

Possible ways to find duplicates. This is not a problem for 10k+ users, who can see deleted posts - they see the content of the post and also the duplicate. The duplicate target could also be found using SEDE, since the Postlink table contains also the links for deleted posts. In some cases, Wayback Machine could help with finding some version of the question. Also the link of the form /questions/linked/qid works for deleted questions, too and that also reveals the duplicate target. But I'd guess that a user who is not very familiar with Stack Exchange would probably not think of these possibilities immediately.

There already exists a way in which anonymous users are redirected to duplicate targets - here is the corresponding feature request, which is marked : Automatically redirect anonymous user from unanswered duplicate question to corresponding answered version.

Feature request:

  • Make the redirect for anonymous users to the duplicate target work also in cases when the question is deleted.
  • For low-rep users (which do not have the privilege to see deleted questions) show somewhere that the question was a duplicate and add a link to the duplicate target. (If there are multiple duplicate targets, show all of them.)

EDIT: To have at least some data on numbers of such questions, here are some SEDE queries. (Take them with a grain of salt, since this is my very first attempt to make a multisite query and I do not have much experience with SQL. Still, I hope that the result should be at least approximately correct.) Here is the number of deleted duplicates per site. This query calculates what percentage of deleted questions are duplicates - it runs a bit longer. Maybe you might also want to check the list of deleted duplicates on some specific site.

1I am pretty sure that there exist many deleted questions which are linked from somewhere. The specific case which lead me to thinking about this was when I searched for limit of n^(1/n) in Approach Zero, that is a math-specific search engine which is rather popular on Math Stack Exchange. I got as the top result this deleted question from Mathematics Stack Exchange.

  • 7
    Typically, the general advice is to not delete duplicates unless they add nothing in the way of searching for and finding the target question. Commented Dec 10, 2020 at 9:09
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    @SonictheK-DayHedgehog On Mathematics, nearly every recent closed question is deleted. At least that's how it seems. Commented Dec 10, 2020 at 12:56


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