Rewriting URL

[corwin]

I'm doing a major URL rewriting on our site to make the URL more SEO friendly as well as more comfortable and intuitive for our users. Our site has a lot of indexed pages, over 250k. So it will take Google a while to reindex everything.

I was thinking that when Google Bot encounters the new URLs, it will probably figure out it's duplicate content with the old URL. At least until it recrawls the old URL and get a 301 directing them to the new URL. This will probably lower the ranking of every page being crawled.

Am I right to assume this is what will happen? Or is it fine as long as the old URLs get 301 redirect?

If it is indeed a problem, what's the best solution? rel="canonical" on every single page maybe? Another approach?

Thank you.

[ORob]

From what I've seen, Google is sophisticated enough to look at the bigger picture of your content - prior to handing out penalties. It is likely they will compare the two pages, identify the duplicate content, hit the 301, and proceed with that directive. If you've set it all up properly you should be alright once they get through all of that crawling.

[corwin]

Thanks Owen, I hope you are right.