Google's Big Daddy update - Is your site supplemental?

On the popular WebmasterWorld forum, many webmasters have reported that all of their web pages except for their index page have been moved to Google's supplemental index.

What are supplemental results?

Supplemental results in Google are from an alternate index. Google usually only uses this index if they cannot find relevant results in their normal index. That means that this index is only used for very obscure queries.

Google augments results for difficult queries by searching a supplemental collection of web pages. Results from this index are marked in green as "Supplemental."

Being in the supplemental index generally means that your web pages won't be included in the result pages for normal queries anymore.

How can you check if your web pages have gone supplemental?

Perform a Google search for site:mydomain.com (replace mydomain.com with your own domain name). If you see "supplemental result" next to the snippet then your web pages are supplemental.

Why does Google put so many web sites in the supplemental index?

It seems that this is simply a bug in the transition to the new Google data centers. One of the main reasons for Google's latest update was that Google wanted to solve problems with canonical URLs.

It might be that Google makes some web sites supplemental to identify the main domain of the site. Then Google might respider these sites using the new algorithm that can better handle canonical URLs.

What can you do if your web site is affected?

In the WebmasterWorld forums, a Google employee who posts under the name Googleguy asked webmasters to send their feedback to Google:

"I'm happy to ask someone to check this out. Please send an email to sesnyc06 [at] gmail.com with specific domains and the keyword 'gonesupplemental'.

I have a theory about this, which I'm asking the crawl/index guys to check out, but I'll need 5-10 specific examples to check if my theory holds. If my guess is right, I'll try to get the crawl/index folks to get things back to the previous behavior."

You shouldn't worry too much if your web site has been moved to Google's supplemental index. As soon as Google has rebuilt the new index, your web pages should be back in Google's main results.

If your web pages are still in the supplemental results in a week or two, contact Google at the email address mentioned above.