I think with the scale requirements of YouTube, we can not assume that the search is powered by one single DB or any traditional, relational DB at all.
Some things that are easy with one DB, get surprisingly hard when you scale up. Lets give them the benefit of the doubt regarding technical issues here.
I don't give them the benefit of the doubt, because they should have had proper testing in place before anything like this reached production. This is either intentional or grossly negligent.
Some things that are easy with one DB, get surprisingly hard when you scale up. Lets give them the benefit of the doubt regarding technical issues here.