Inverted indices were not used as they worked poorly for “an ordered list of words” (as opposed to a bag of words).
And this doesn’t even start to address the ranking part.
Wikipedia [1] links to "Jeff Dean's keynote at WSDM 2009" [2] which suggests that indices were most certainly used.
Then again, I am no expert in this field, so if you could share more details, I'd love to hear more about it.
[1] https://en.wikipedia.org/wiki/Google_data_centers
[2] https://static.googleusercontent.com/media/research.google.c...
You can solve the ordered list of words problem in ways that are more efficient than grepping over the entire internet (e.g. bigrams, storing position information in the index).
Various ML "learn-to-rank" tooling was in use at Google for a while, but incorporating document embedding vectors w/ ANN search into the ranking function probably happened over the course of 2018-2021 [1], I think. Generative AI only started appearing in ordinary search results in 2024.
1: https://cloud.google.com/blog/topics/developers-practitioner...
A related takeaway should be that machine inference is pervasive and has been for years, and that defining "AI" to mean just chatbots is to ignore most of the iceberg.
Not just "one training run," but the cost of a thousand AI engineers starting failing runs to get to that one deployed model.
1: Link to Google's tech report: https://services.google.com/fh/files/misc/measuring_the_envi... "We leave the measurement of AI model training to future work."
From 2022, so possibly out of date: "ML training and inference are only 10%–15% of Google’s total energy use for each of the last three years, each year split ⅗ for inference and ⅖ for training." That's probably close enough to estimate 50/50, or the full energy cost to deliver an AI result is double the inference energy.
https://research.google/blog/good-news-about-the-carbon-foot...
I'm honestly surprised that they're so similar. I've thought of LLM queries as being far more energy-intense than "just" a Google search, but maybe the takeaway is that ordinary Google searching is also quite energy-intense.
If I as a user just wanted an answer to a dumb question like, say, the meaning of some genZ slang, it seems about an order of magnitude to ask a small LLM running on my phone than to make a google search.
(Check my math: assuming the A16 CPU draws 5 watts peak for 20sec running Gemma or whatever on my iPhone, that’s 0.03Wh to answer a simple query, which is 10x cheaper)
Are training costs (esp. from failed runs) amortized in these estimates?
1: https://googleblog.blogspot.com/2009/01/powering-google-sear...