I upgraded my site so that all pages have gone from using HTTP to HTTPS. I didn't consider that Google treats HTTPS pages differently than HTTP. I recreated my sitemap to so that all links now reflect the new HTTPS URLs and let it be for a few days. (Whoops!)

Google is now re-indexing all the HTTPS pages. I have about 19k pages on the site, and Google has already indexed about 8k of the new HTTPS pages. The problem is that Google sees all of these as brand new pages when many of them have a long HTTP history.

Of course most of you will recognize the problem, I didn't set up a 301 from the old HTTP to the new HTTPS URLs. Is it too late to do this? Should I switch my sitemap back to HTTP URLs and then 301 redirect to the new HTTPS URls? Or should I leave the sitemap as is, and setup 301 redirects anyway... I'm not even sure if Google is trying to reach the HTTP site anymore. Currently the site is doing 303 redirects (from HTTP to HTTPS), although I haven't figured out why yet.