I don't even know if anybody has written a book specifically about search at "web scale" (no MongoDB jokes here, please). But about the closest things I know of would be something like:

https://www.amazon.com/Managing-Gigabytes-Compressing-Multim...

https://www.amazon.com/Information-Retrieval-Implementing-Ev...

https://www.amazon.com/Introduction-Information-Retrieval-Ch...