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minor typo
Martin Sleziak
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While 6005's answer gives a quick-and-dirty way to find the first use of a tag with very high probability, there are a couple of situations where it will not return the correct information.

  1. After being created the tag is edited into an older question.
  2. After being created the tag is removed from that question.
  3. The question where the first use occurred was subsequently deleted.

There is very little that can be done about the last problem, but the SEDE can help with the first two. This query goes through the PostHistory table, and finds the earliest 10 revisions where the specified tag was used. There are a couple of things users should be aware of when using this.

  • There may be "false" results in that if userAlice edits into a question, and userBarbara later edits that question's tags but retains , then userBarbara's revision might also appear when looking for tagname in the query, even though userBarbara really didn't add the tag to the question. (It all depends on how many other "tag revisions" with there have been between userAlice's and userBarbara's revisions.) The first line will in all probability be the first use of , excepting some cases noted below.
  • The data in the SEDE is only updated every Sunday at about 03:00UTC, so if you are looking for the first use of a very new tag this query will not help: it will return nothing.
  • Deleted questions are not included in the PostHistory table, so if the question where the tag was first used was subsequently deleted, this query will not grab that first instance. (I could try to additionally go through the PostsWithDeleted table, but similarly to the Posts table one would only find posts to which the tag was attached at the time of deletion, so the combination of cases (2) and (3) really is insurmountable, as far as I can tell.)
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