Correct me if I’m misunderstanding. Refer to the following sentence:
Stack Overflow copied a key part of the Wikipedia database design.
This turned out to be a mistake which will need massive and painful
database refactoring to fix. The refactorings will be to avoid
excessive joins in a lot of key queries. This is the key lesson from
giant multi-terabyte table schemas (like Google’s BigTable) which are
completely join-free. This is significant because Stack Overflow’s
database is almost completely in RAM and the joins still exact too
high a cost.1
Actually I’m trying to pass from the interest on single technology like Asp.net MVC to architectures design.
Can you better clarify the quoted sentence?
[1] http://highscalability.com/stack-overflow-architecture
You’ve misread the directionality of the quote.
JOINs are generally discouraged for high-volume systems, because they are expensive (because of I/O being necessary more than one table). SO put their database into RAM specifically to avoid being hit by double disk I/O costs, and it turns out that even without physical I/O, the double table searching is still too slow. That shows you just how inefficient JOINs are on large volumes of data.
1