As I have said in my previous post, supplemental index was a garbage dump of pages that Google considered low value. It was queried only if nothing good could be found in the main index.
Now Google promises to pay more attention to this index. The pages in the supplemental index will be crawled at least every three months and it is reported that some time in future the Googlebot might start crawling them every month. Google also claims that they might begin indexing urls that have more parameters. This shall help your previously supplemental pages find a place in the main index, and rank better. It is a good news.
However, I feel that the three-month crawling interval is too long and hence any changes that you make to the supplemental indexed pages might go unnoticed for a long time. Also removal of the tag makes it very difficult for you to know which pages need some revision for it to be pushed back to main index.
Until Google adds a tool within their Webmaster Central platform to help you see your supplemental pages, there is no accurate way to know what pages of your site are in the supplemental index.
However with some intuition, you should be able to make some educated guesses of which pages are in supplemental database.
Check in Google if a page of your site has been indexed. If yes, check the cached link. If the cache date is more than a month old, it is likely that Google is not giving the page much of importance and it is quite possible that the page has slipped into the supplemental index.
How to get better of this invisible supplemental tag
Bear in your mind that even if there is no supplemental tag ahead of the pages indexed in Google, some of these pages may be in supplemental box. Follow the below rules and do not let your pages slip into supplemental index.
ü Write unique readable and indexable content
ü Write unique meta tags and titles
ü Attain some backlinks to the inner pages
ü Avoid deep linking your pages
Filed under: SEO
