It would be a neat feature for the Community bot to automatically detect when the last users posted question StackOverflow question is identical to their last posted question on any other Stack Exchange site.

For example:

  1. User posts a poor question on StackOverflow and it receives no attention after a few hours

  2. User gets impatient and posts the exact same question on Programmers hoping to bring attention to a different audience.

  3. As a Programmers mod, we have become accustomed to the duplicate SO question check as a manual process, because this happens all the time. We spot this and close the question as off topic.

It may seem like an expensive check to perform when a question is posted but not if the question body is computed and stored as a hash in a seperate field. Comparing identical hashes would be much cheaper so it is certainly a feasible feature.

I also see the benefit for other Stack Exchange sites as well. I post a question on Mathematics and it is not answered, so I immediately cross post onto Cross Validated hoping to double the chances of getting an answer. Without this feature, many of these occurrences may never get caught.

When this situation is caught a simple Community Flag brings it to the moderator attention where we can handle it from there.


A simple version of the same process is one where somebody links to their existing question from another Stack Exchange site. This can also sometimes be something that a moderator may want to look at.

  • 4
    Identical post detection already occurs on the same site, so it can't be that expensive. – user102937 Oct 24 '12 at 19:35
  • It kind of is -- every site is its own database. Isn't querying across databases really hard...? – Aarthi Oct 24 '12 at 19:39
  • @Aarthi Web services are the name of the game, and nobody said that it has to be an immediate check. It can be incorporated into a scheduled job where lastest question hashes can retrieved from other sites and compared. – maple_shaft Oct 24 '12 at 19:42
  • 5
    Querying all other sites would probably be a waste since most of them are unrelated. Also only going to get more and more expensive as the network grows. – Adam Lear Oct 24 '12 at 19:53
  • 2
    Do sets of related sites with perhaps a relation weight governing how often the check is performed? Like Programmers and Stack Overflow check each other every five seconds (maybe not that often :P) whilst Photography and History check each other perhaps once a week? Maybe adjust the weights over time given how many question dupes were found? – World Engineer Oct 24 '12 at 19:56
  • Stop stealing my ideas @maple_shaft ;P – yannis Oct 24 '12 at 21:35
  • @YannisRizos Never found it... doesn't count ;-) – maple_shaft Oct 24 '12 at 22:26
  • @maple_shaft Well, it's an answer, it wouldn't come up in a search (even if you had searched ;). I think the question is a duplicate though, but I really don't want to vote to close it, it's been ignored for quite some time and we really need an easier way to catch cross posts... – yannis Oct 24 '12 at 22:29

The only version of this I could see potentially being useful / inexpensive is when the "check" would scan all sites in the default migration shortlist. Since those are supposed to be the most-likely-to-be-migrated-to sites, it would make sense for an auto-check to run when someone is asking.

The problem then is that even between the trilogy of sites, the default migration shortlist isn't fully consistent. So, someone asking a question on programmers that most would assume would originally be asked on SO but that should be asked on Webmasters might not actually happen. On the other hand, the check would find the closed/deleted/migrated question SO anyway.

I think this is a pretty sticky situation and one that would, as Anna Lear pointed out, become expensive over time as the network grew. If we could pick a good limited set of potential sites, it might be more feasible.

  • 2
    Thanks for bolding my name. NOW THEY ALL KNOW I'M HERE. hides in the corner – Adam Lear Oct 26 '12 at 0:04
  • @AnnaLear Welcome to the Hotel Stack Exchange. /me steals from Shog – Aarthi Oct 26 '12 at 15:04

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .