Back in 2005 Google and Yahoo would compete over the size of their search engine index. That competition somewhat ended at the end of 2005, you can learn more about that over here.
But then came the How Search Works portal from Google that first touted 30 trillion pages and then grew to 130 trillion pages that Google is aware of on the web - not necessarily indexed. That was back in November 2016 and sometime after, Google dropped the metric from the How Search Works portal.
Now, we have a well respected software developer named Tim Bray who worked at Google, Sun Microsystems, the Digital Equipment Corporation (DEC) and several start-ups and now is at Amazon's AWS team. He wrote a blog post named Google is losing its memory and showed two examples of how both Bing and DuckDuckGo were able to find a page that Google was not able to find.
It caught Danny Sullivan's attention on Twitter, which Danny responded that "I wouldn't make that assumption for the entire web based on what's happening with only your site." Tim being respected, Danny said he would dig into it, believing it may be an issue with the two example sites he cited, even though Bing and DuckDuckGo was able to index and return the content in their search engines.
Danny wrote:
Well, I wouldn't make that assumption for the entire web based on what's happening with only your site. But something weird does seem to be happening with your site, so passing it on and checking on it.
— Danny Sullivan (@dannysullivan) January 15, 2018
Yes I realized that after. Checking on them both and the issue in general.
— Danny Sullivan (@dannysullivan) January 16, 2018
It should be fun to watch if this goes anywhere or not.
I should add, those pages are now in Google's index, but Tim brought attention and links to those pages, so that helps Google index stuff.
Forum discussion at Twitter.