How do I transition to SSL without affecting PageRank?
Your proposed solution is the best way forward from an SEO perspective. You avoid duplicate content by using the canonical URL and the 301 redirect will transfer most of your PageRank (a small amount is lost in the redirect). Plus thanks to the strength of Stack Overflow's pages in Google I would be more then stunned if you saw any fluctuations in your rankings. Smaller sites would see a transition period in their rankings while Google got caught up with their new URLs but I don't forsee that happening to Stack Overflow.
FYI, John Meuller, the Google employee you quoted, is an active member here. With a little luck he'll give us his perspective on this.
About a year ago there was a bug in the permalink generating code for my WordPress site, which gets about 70% traffic from Google. The canonical tag started using the WP short URL format instead of the regular format.
Two weeks later, I found the bug when I noticed that my URLs were showing weird in the Google index. Instead of the full /999999/post-url-format-like-this/ in the results, it was showing ?post_id=99999 (or something similar).
There were no changes in traffic.
The bug was fixed, the canonical tag properly set again, and about a week later, Google had adjusted all of the indexed links back to the normal format. Painless, really.
So based on my experience, your plan should be:
- Change the canonical tag to point to the HTTPS URL instead.
- Google will automatically update all of the results in the index. This might take a few weeks and requires no 301 redirects. And... 95% of your traffic will be using SSL.
- Redirect logged-in users that click from another site.
Since 301 redirects do remove some of the pagerank, I don't see the point in using them right away, especially since the canonical tag should take care of the Google index.
I believe Google ranks the first URL seen should it be a short URL, HTTP or even HTTPS unless a canonical link has been used so right they are separate rankings so 301 transition would result in some juice lost in the transition.
However as John has also said its doubtful this would hurt stack, since stack has tons authority and trust with Google.
Also for all we know Google may even increase stacks rankings for going SSL since its making the site more secure for its users which in effect increases user experience which Google strongly believe in. Though this speculation but its good to be hopeful? :)
Also:
Google’s Matt Cutts said on a Hacker News comment that those who are interested in switching their whole web site from HTTP to HTTPS should go ahead and do that.
- Google, want to switch to HTTPS? go ahead
- Hacker News, Facebook starts switching all users to HTTPS connections