There are maybe 20 people the world who 'know' how to scale a website up to millions of users. There are lots of teams of hundreds of people who actually do it.
Don't get worried that you won't be able to go in and run the show on the first day. There isn't any secret sauce, and sites that scale to this level are so rare that they probably each have their own arcane and complex way of doing it that has evolved over years of people trying different approaches and failing.
Anywhere that is worth working isn't looking for someone who knows how to scale a website to millions of users, they are looking for smart people who can contribute. Their development budget is probably in the millions of dollars per year, they will be more than happy if you can help.
TLDR; Nobody is going to write a book on this, since only 500 people in the world would benefit from reading it. There is no single answer.
To address the specifics of what you are asking, there is basically a balancing act of consistency vs performance. You need to find the exact balance that is 'good enough' for every problem. The oft quoted 'there are two hard problems in CS, cache invalidation and naming things' pretty much sums it up.
Don't get worried that you won't be able to go in and run the show on the first day. There isn't any secret sauce, and sites that scale to this level are so rare that they probably each have their own arcane and complex way of doing it that has evolved over years of people trying different approaches and failing.
Anywhere that is worth working isn't looking for someone who knows how to scale a website to millions of users, they are looking for smart people who can contribute. Their development budget is probably in the millions of dollars per year, they will be more than happy if you can help.
TLDR; Nobody is going to write a book on this, since only 500 people in the world would benefit from reading it. There is no single answer.
To address the specifics of what you are asking, there is basically a balancing act of consistency vs performance. You need to find the exact balance that is 'good enough' for every problem. The oft quoted 'there are two hard problems in CS, cache invalidation and naming things' pretty much sums it up.