How permanent is a rel="canonical"?

[CoreyTisdale]

We are rolling out our canonicals now, and we were wondering: what happens if we decide we did this wrong and need to change where canonicals point?

In other words, how bad of a thing is it to have a canonical tag point to page a for a while, then change it to point to page b?

I'm just curious to see how permanent of a decision we are making, and how bad it will be if we screwed up and need to change later.

Thanks!

[AdoptionHelp]

If you decide to change things later you can update your canonical tags and/or use a 301 redirect. Based on the information on the Google webmasters blog, it appears they consider the canonical tag on every crawl. You can read more from Google on it here:

http://googlewebmastercentral.blogspot.com/2009/02/specify-your-canonical.html

Of course, just because you can change it doesn't mean you should. Switching them around will probably cause a period in which Google is unsure of the actual canonical page, and you may see a drop in rankings while it is sorted out.

[CoreyTisdale]

Thanks Ryan. I realize the goal is to not redo them, but we had to put in place some pretty in depth plumbing changes on the site to support canonicals, and I suspect we might make a few tweaks once we see how things play out. I think I really needed a confidence boost that canonicals are only semi-permanent. Thanks a lot!