Since their introduction, migrations have been largely well received, but still cause some problems, typically in the area of folks migrating questions to sites they didn't understand or migrating subpar questions.

One of the key guidelines for migrating questions (after "don't migrate crap") is "don't migrate old, answered questions".


We recently disabled migrations on questions older than 60 days, which goes a long way towards resolving problems with such migrations, but does leave two holes:

  1. New sites (like Mathematica) that form successful communities of their own, even if born out of a larger site like Stack Overflow.
  2. Old questions that haven't received answers but fell through the cracks of time.

The second is easy: if the question is off-topic on your site, vote to close it as such regardless of its age or quality. You can leave a comment on the post suggesting a better location. If the asker is still around and interested in the answer, they will be grateful and will repost the question in a better location to get their solutions.

The first, however, requires a bit more of a process. Let's say you're on a smaller site that has grown to the point where you want to start considering picking some canonical questions that have already been asked and answered elsewhere. Here's how you can get some (or all) of them migrated to your site:

  1. Start on your meta. Build a list of questions that you think would benefit from being migrated to your site and collect some reasons along with each one. Don't just say "all questions in our tags!". That's neither going to happen nor is a good approach - do you really want to swarm your new community with old content?

    This is also your opportunity to edit old questions to make them more in line with your scope and standards.

    Once you have your list...

  2. The questions will be vetted by the source community as well. The exact details here are still to be worked out, but the idea is that we would present these questions to the relevant subcommunities of the original site. For example, questions that are candidates for migration to Mathematica would be vetted by the regulars of on Stack Overflow.

    Some form of discussion will ensue and by the end of it we will have the final list of questions to move over.

  3. We will do a one-time mass migration of the questions that make the cut. This has some additional implications. For example, your front page on the smaller site will be more or less destroyed for a bit, so make each question count.

Once this migration happens, the topic is closed. There will be no more discussions, migrations, exceptions, etc. where old questions are concerned. You're free to still edit and migrate new questions if needed.

What happens if some of the questions you wanted don't get migrated? Just treat the original site like you would any external blog. If someone asks a similar question on your site and you're certain that you can't do better than the original version elsewhere, summarize it, give credit to the author, and link back to the original.


In my experience, there are definite reasons to sometimes migrate old questions to new sites, but those are rare and should remain exceptional. This system should hit on those cases, allow both communities to have a voice, and miss ones where a migration would do more harm than good.

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    MIGRATE ALL THE THINGS! – yannis Oct 25 '12 at 21:28
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    Quoting "Just treat the original site like you would any external blog" for Justice! – Shog9 Oct 25 '12 at 21:28
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    I don't see migration as useful at all for canonical questions. These really need to be asked and answered on the site they're intended for. It's for the off-topic questions from the long tail that happened to get a good answer that migration is good. – Gilles 'SO- stop being evil' Oct 25 '12 at 21:34
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    @Gilles We might be treating the word "canonical" a bit differently. To me, a question that got THE answer is the canonical version of that question. On a site like SO, it's also possible that the audience for the question was right at the time when it was asked - SO happened to be where that audience hung out. That said, nothing wrong with re-asking either. – Adam Lear Oct 25 '12 at 21:38
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    @AnnaLear “Canonical question”, on Stack Exchange, usually means an instance of a question that comes up often, which is well-curated and that many questions get closed as a duplicate of. If that's not what you mean, please clarify. What you describe in your comment sounds like a long tail question that got a very good answer. – Gilles 'SO- stop being evil' Oct 25 '12 at 21:48
  • @Gilles: the canon for niche topics can be fairly long-tail. I think what Anna's getting at is that it doesn't really make sense to migrate questions that won't be broadly useful on the newer site - by the time this is even possible, they'll have spent months or possibly years growing their own tail, and more importantly identifying linchpin topics that benefit from exactly the sort of active curation you refer to. – Shog9 Oct 25 '12 at 23:12
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    So, all this well-thought-out, helpful policy is nice and all, but I have to be honest: My +1 was mostly for "amble". – Jaydles Oct 26 '12 at 15:01
  • Hello Anna Lear! Do we have a due date for when this information has to be in by? If possible, I'd much prefer to add a due date on my own meta so that we don't come to you 6 months later with a list. Thank you. ;) – jmort253 Nov 6 '12 at 1:53
  • @jmort253 There's no due date at this point. Although I will note that it doesn't apply to your site since you're still in beta (unless you mean something other than PM?). – Adam Lear Nov 6 '12 at 2:48
  • @AnnaLear - Thanks for clarifying. I mistakenly thought this applied to betas too. – jmort253 Nov 8 '12 at 8:04

I see this as being fine for most sites except for Stack Overflow for two reasons.

The first is the sheer size of Stack Overflow. You can't expect someone to curate all the content in a single tag on Stack Overflow and expect it to be comprehensive in any way. To close off the avenue for migration at a later point seems to limit the options too much when the source site is Stack Overflow.

The second is how on topic a question is on the source site. If the question is clearly on topic on Stack Overflow, there is no reason to have it migrated to another site, no matter how badly they want it.

It was explained to us at one time that we should be jealous of our sites when it comes to the topic of migrations, and that stuck. If a question is on topic, answered on Stack Overflow, there's no reason for it to be migrated anywhere.

Granted, there's a little bit of pride in the second point, but that was the point behind what we were told; the question lived here for a long time, we put the work into it, there's no reason that we shouldn't be the one to keep it if it clearly has had a place here for so long.

There's no perceptible benefit to a source site that migrates questions away that are good and on-topic. Yes, there's absolutely a benefit for the destination site, but if it's at the cost of another site (even one as big as Stack Overflow; the argument "you can handle it" isn't acceptable) then it absolutely should not happen.

Finally, there's a huge concern about moderators from the source site (they are not included in who would be consulted on the source site) being involved with the process. As moderators, we are expected to be able to moderate content across all the tags; we aren't expected to be subject experts in every tag, but we're expected to be able to identify good quality, on topic content when we see it (as well as the inverse of that).

If as moderators we are able to do that, there's no reason we shouldn't be able to participate in determining which questions from the source site should go and which should stay, we wouldn't be moderators if we weren't expected to be able to do that in the first place.

Something to consider:

You're an active user on your site. You're passionate about the site and the quality of content on your site and constantly work towards constantly improving it. Yes, you know that there's overlap with another site, but your site is successful because it doesn't need the content from the overlapping site.

Now someone from that other site wants to take that content, as it's on topic for both and now able to be considered for migration due to this proposal.

What's the benefit to your site? Why does a site that has proven that it doesn't already need the content from your site get to take away something that it doesn't need, and will harm you in the process?

How does taking quality content that is on topic for help that site, or at the least, not harm it in any way?

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    Given the constrained scope of Stack Overflow nowadays, it is highly unlikely that any new Area51 proposal would be able to mine any questions from SO unless they're very old. The scale of such questions may be smaller than you think, and they might actually be questions we'd be glad to finally find a real home for. – user102937 Oct 25 '12 at 21:56
  • @RobertHarvey I don't disagree. Admittedly the specific example (Mathematica) has been pretty aggressive about wanting to take some of our old, good posts that are clearly on topic here. That's the basis for most of the response. – casperOne Oct 25 '12 at 21:58
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    Pffft, who wants SO's questions anyway... – yannis Oct 25 '12 at 22:01
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    This is kind the point of Step #2... And of making this a one-time deal for spin-off sites. You know as well as anyone some of the tension that's surrounded this process in the past. This is intended to be an opportunity for the parent and child sites to work together on hashing out what belongs where, without the sort of long-term frustration that ad-hoc migration of old questions was prone to generate. Oh, and regarding the size: no plans to spin off [java] any time soon; the largest spin-off yet has been DBA, and that only counts if you consider everything in the [sql] tag on-topic. – Shog9 Oct 25 '12 at 22:40
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    casperOne, I'm a Mathematica ♦ -- this is the first I've heard that our requests for migration were not looked upon kindly. Nearly the entire Mathematica user base has moved to the new site, joined by a host of new users who were never on SO. (By third-hand account a lot of users were put off by the general traffic on SO.) If the two sites were vying for the same users I guess I'd see your point but they're not. If nobody is there to read them are the old posts still "good" on your site? – Mr.Wizard Oct 26 '12 at 0:39
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    @Mr.Wizard your mistake is in thinking that we're vying for the same users, were not, I'm vying for posts. And this conversation was had in the last two weeks in TL. – casperOne Oct 26 '12 at 1:47
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    As an aside, the fact that a prominent user (and a moderator) on Mathematica wasn't even aware of this discussion seems like a good argument for not having these discussions in TL. – Adam Lear Oct 26 '12 at 2:58
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    @Mr.Wizard - Keep in mind that there are likely people who search for answers on Google and get redirected to the old Mathematica posts on Stack Overflow. Most sites traffic actually come from search engines, so that's something to take into consideration when you decide whether or not you want those questions ;) There are definite pros as well as cons when it comes to leaving them here. I'm wondering if it would be better to edit the posts or mark in the tag wiki that new questions can be asked on Mathematica SE. Would that be better SEO or no? – jmort253 Oct 26 '12 at 8:12
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    @Mr.Wizard Sorry, I was incorrect about the entire thing, the conversation wasn't two weeks ago, it was a long time ago. The conversation I was thinking of was with moderators of another site that wanted to change the tag wiki in a way that indicated that programming questions about their site's topic were off topic for Stack Overflow, when that isn't the case. Sorry for the misunderstanding. – casperOne Oct 26 '12 at 13:30
  • @AnnaLear They couldn't be aware because I was mistaken, see ^^^^ – casperOne Oct 26 '12 at 13:30
  • @AnnaLear Any comment on why moderators would not be involved in the process? – casperOne Oct 28 '12 at 1:55
  • @jmort253 the SO "mathematica" tag wiki currently directs users to the new site but questions continue to trickle in. Given that many Mathematica users are not general programmers I think that finding Mathematica.SE through search, rather than Stack Overflow, would be more helpful. – Mr.Wizard Oct 29 '12 at 15:54
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    @casperOne I still don't understand. If the Mathematica community has moved to the new site how would migrating a question like that (old, highly ...) harm Stack Overflow? Unless I'm blind you still haven't answered that. – Mr.Wizard Oct 29 '12 at 18:52
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    Quality content is not useful if no one would look there in the first place... which is how Stack Overflow is perceived in the Mathematica community. Mma questions on Stack Overflow is about as helpful as Eric Lippert's answers on Mi Yodeya or Role-playing Games. Even though there is a path to it from Google searches, people just don't relate the subject with the site. – Lorem Ipsum Oct 29 '12 at 23:16
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    I don't think pride, jealousy, or (frankly) selfishness are valid reasons for keeping a good question with a limited audience on one site when there is a much larger audience for that question on a different site. I'm with @Mr.Wizard here. So what if the other site doesn't technically need these questions (whatever "need" means here -- I think that term is too vague to be useful here). If a different site is where most of the question's audience is, that's where the question belongs, even if it is still on topic on its original site. – Ben Lee Nov 1 '12 at 19:04

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