Huge e-commerce site migration - what to do with product pages?

[FPD_NYC]

My very large e-commerce client is about to undergo a site migration in which every product page URL will be changing. I am already planning my 301 redirect process for the top ~1,000 pages on the site (categories, products, and more) but this will not account for the more than 1,000 products on the site. The client specified that they don't want to implement much more than 1,000 redirects so as to avoid impacting site performance. What is the best way to handle these pages without causing hundreds of 404 errors on site migration day?

Thanks!

[responsivelabs]

What language is the new site coded in? You can always create a redirector within the new sites code all at once using a database query and amending a URL. This will prevent you from having to create such a large .htaccess file for redirects. I may be able to help you if you let me know which language you're using along with providing examples of the type of redirects you'd like to setup.

[FPD_NYC]

The new site will be built on the Oracle ATG platform. Does your method still return a 301 response code?

[responsivelabs]

Hmm, I'm not too familiar with Oracle ATG. Is that Java-based? I mainly work with PHP. To answer your question, yes it does return a clean 301 redirect response for crawlers.

I came across this link on Oracles doc for ATG. It looks like you could possibly use the URL templates to accomplish this. Do the URLs that you plan on redirecting have a commonality between them? (ie. switching 100 URLs from http://example.com/example1/* to http://example.com/*). If so, you can possibly separate them into these common "groups" and develop a redirect for each group instead of each URL.

[Everett]

They are changing from what old format to what new format? Sometimes, if there is logic to the URL structure, you can handle thousands of redirects with only one line of code called a regular expression.