The following just happened to me here:

  • I posted a comment on a question:

    Related: [Link to other question]

  • I made up my mind and decided that the related question was not only related but a duplicate.

  • I deleted my comment, figuring that a comment would be generated when I voted to close as a duplicate.

  • I voted to close as a duplicate.

  • No automatic comment was generated.

  • I manually generated a “possible duplicate” comment.

Going by the comments and answers to this question, the comment is not generated, if the duplicate question is already linked in an existing comment. This is okay by me, but this search should not take into account deleted comments, because then we end up with the duplicate being unintentionally linked nowhere.

Depending on how exactly the comment generation works, excluding deleted comments might also address this problem.

marked as duplicate by Shadow, Community Jul 30 '15 at 11:15

This question was marked as an exact duplicate of an existing question.

  • I think it is not based on linked in an existing comment but linked in the PostLinks table, which gets an row as soon as a comment with a link to an existing question is posted. The postlinks table either lags behind or isn't refreshed at all when the facts that created the rows are un-done. – rene Jul 30 '15 at 9:18