Sopli, or Google's Supplemental Index

Practice

In the article where we talked about on-page site optimisation, we mentioned some of Google's “sopli” — Runet SEO slang for what's officially called the Supplemental Index.

And naturally, a lot of people got curious what that actually is. Although you can probably guess from the name that it's not about anything good. Or, more precisely, about yet another way Google fights search spam.

What is Google's Supplemental Index

Back in 2003, to optimise its search database, Google launched the supplemental results mechanism (Google's Supplemental Index), aimed at dealing with web pages that carry no value from the search engine's point of view.

On one hand, this is a big plus, because when a person is searching for information they need, Google does everything it can to give the user relevant pages for their query. But on the other hand, for site owners, these supplemental results are not such a great thing

So what's wrong with the Supplemental Index

The main problem with this index is that it doesn't bring the site's users any visitors at all from the search engine.
Since the crawler is only allotted a certain amount of time to scan a site, it's a real shame if the crawler spends that time on pages that aren't very valuable to people or to search engines.
A large number of pages in the Supplemental Index has a negative effect on the site's overall ranking in the search results.
If you have a huge number of pages in the Supplemental Index, it's fair to assume Yandex will take a similarly negative view of those pages. Except in that case, Yandex will simply exclude your site from its results altogether.

Why pages end up in the Supplemental Index

So, let's work out which pages are at risk of ending up in the Supplemental Index.

The site's pages have duplicate content.
The page has no text at all.
Pages with duplicate titles and meta tags.
Pages that have no titles or meta tags at all.
Pages that are very hard to reach. Such pages typically have a nesting level greater than 4.

How to find out how many of a site's pages are in Google's Supplemental Index

To find a site's pages in Google's Supplemental Index, you used to be able to use the Google operators
site:site.com -site:site.com/&
The operator site:elims.org.ua/& shows how many pages are in the main index.
The operator site:elims.org.ua shows how many pages there are in the index altogether.

But recently this combination of operators has stopped working. And now, to find out how many pages of the site are in the Supplemental Index, you need to use the operator site:site.com to page through all the pages of the main index until you reach the link “We have hidden some results that are very similar to the ones already shown above. Show hidden results.” After clicking “Show hidden results,” you will see how many pages you have in Google's Supplemental Index.
Of course, there's an easier option. To do this you need to install the RDS bar plugin in your browser.

After clicking the button, a window will pop up where you'll see something like this.

As you can see in the image, it shows as a percentage how many pages out of the total index are in the main one. The rest of the pages are in the Supplemental Index.

Of course, not 100% of pages can be in the main index. But if you're seeing roughly the same figures for your own site, then you're in good shape. And if not, then you need to get those pages out of the Supplemental Index.

How site pages out of the Supplemental Index

The most important thing is to fill the site with unique content.
Remove pages that have no value.
To remove unnecessary pages you can use methods such as these.
- Block unnecessary pages from indexing in the robots.txt file.
- Block unnecessary pages from indexing via the robots meta tag.
- Block unnecessary pages from indexing via the X-Robots-Tag http headers.
- Set the rel="canonical" attribute on all pages. We wrote about this attribute in more detail here.
- Delete the page in Google's webmaster panel.
Work on your site's structure so that the nesting level of your site's pages is no higher than the fourth. And, of course, you should try not to exceed that level going forward.