It is a well-known problem that a Google search for something in the PostgreSQL documentation will usually return hits in old documentation versions first, because those pages have been around for the longest.
I believe I have a promising fix for that. By adding a <link rel="canonical"> to the documentation pages that point to the "current" version, search engines will be encouraged to return the current version search results.
I think this is worth trying. A one-line patch is attached.
By that article you linked, it's important not to link to pages that don't exist. So we should at least verify that the page does exist in the current version (the same way that we do for the links at the top of the pages for old versions). IIRC someone (sorry, this is a long time ago, can't remember who or why) mentioned that the pages can get severely punished if the canonical link goes to a 404.
We did try this at some point ages and ages ago and it didn't help, but I agree it's probably worth another try. But we definitely need to be careful not to destroy existing google ranking.
And FWIW, the django way isn't particularly good either. For example a google for "django 1.8 models" only gives me the 1.10 documentation. But that may still be the lesser of the two evils.
Also, when I search for it, I always get the greek version (el) first (though it's in english), followed by japanese. The actual page to look for doesn't show up until the 5th spot. Which goes to prove that no way really works *well* :S
