How does google fetch results

Not the algo...how does it dip into its database?

[sahuman]

I understand this a newbie question, but I have always wanted to know how does Google fetch its results. No, I don't want to know the algo!

Suppose I type in "Blue widgets" in my browser and press "search"...what does Google do next. I don't think it scans a couple of billion pages, select those that have "blue widgets" in it, applies its algorithms and displays the top 10 that it thinks is most relevant. That would take ages and a huge amount of resources.

Technically, how does Google maintain its database or index? And how does it bring up results in a fraction of a second from a billion pages?

[oldskool79]

I'm no expert on this, but I'm pretty sure Google has creates an index that works the same as the index in the back of a book.

Let's say you search for "blue widgets". Google will then look up "blue" in it's index and get a list of all the pages that contain that word. Then it will do the same thing with the word "widgets".

Out of these two sets, Google takes only the pages that have both "blue" and "widgets" in them. At this point, Google applies it's algorithm to determine which sites should rank where, and then sends them to the browser.

This is obviously a greatly simplified example, but it's the basic idea.

[charlier]

Read all about it:

http: //www-db.stanford.edu/~backrub/google.html

It may be a bit dated now but the structure is probably close to the orginal.