[Benjammer]

You said "There's nothing to index," as if Google is making web requests to every domain in existence, parsing the document responses, and seeing which sites have these words on them, all at runtime when you type a search query. Google obviously indexes the web in the sense that they store their own cached versions of web pages "locally," on top of which they then build an insanely complicated, web-facing, search architecture.

[logicallee]

we're talking past each other. sova referred to this meaning - https://en.wikipedia.org/wiki/Database_index when they said "clever indexing."

the sense you mean is a different sense of the word index - meaning, to crawl. Yes, of course it does that too.

[sova]

I was not referring to database indexes. That is not pertinent here. I was thinking about the index that Google creates, its locally cached version, that it queries. If you have a locally cached version, you are not going to rifle through them one by one until you find matches, nor are you going to rifle through them and find partial matches and then intersect them all to see if any overlap in your final product. Among other weird assumptions, that final method assumes there is a solution for every query.

Google, no doubt, has a very sophisticated way of querying against their cache of the WWW and it has probably evolved over time. However, it is inappropriate to say Google does a join over the entire internet for one query. It is much more reasonable to say that Google checked your query string against their gigantic index of terms, and it took a while to dig that deep into the pile. The performance hit such a complex query takes is more like unzipping a large archive to get a specific megabyte's worth of info, rather than saying it smashed all the files together and then searched for the exact term like notepad.

Anyway, think about it for a while, it's clearly a cool issue in search, and programs and algorithms do not have to visually search things as humans must.