Why does Google greatly limit search results if I am logged in?

Question

I would be interested to see the behavior for other users. This seems to be the case with any search under my account. For example, https://www.google.com/search?q=programmer tells me there are 234 million results on page 1, but returns only 3 pages. When I get to the 3rd page it reports that "Page 3 of about 236 results" and that is the end of my search. This truncated search results behavior occurs with every search term I have tried and I have noticed that if I log out I can continue to see page after page of results. What is even stranger and somewhat unsettling is that I get different results depending on who I am logged in as. If I log in under a relative's under-used account they see 274 million results and can view all pages as if they are not logged in.

salawat · Accepted Answer

Welcome to personalized search results, and the phenomena known as "filter bubbles".
This is what happens when a search engine forsakes it's original mission (providing an index of the whole indexable net while elevating certain results based on a Boolean query), and starts leveraging hidden state to omit what "isn't relevant" by their estimate.
Welcome to the Internet brought to you by "helpful people that think they know more about what you're searching for than you do".
We'll not even go into the agenda or jurisdiction driven omissions to the landscape of the Internet facilitated by corporate interests enforcing artificial scarcity.

smartician · Answer

Multiple things could be at play here. Google Search runs hundreds of experiments. Every time a parameter is tuned, or a snippet of code in one of the dozens of components that make up search is changed, that change is being canaried in an experiment. Users are randomly assigned to cohorts for these experiments (either based on their user ID when they're logged in, or a temporary user ID when they're not). Also, every search request will hit different servers holding different states, and sometimes processing components may time out intermittently. As a result, every user will see a slightly different set of results, or experience other diverging behavior like the truncation you're seeing. This might give the impression of personalized results, which in reality is not happening (only ads and other content that enhances the SERP are personalized).