How do large-scale sites and applications remain SQL-based?
One of the leading motivators for NoSQL innovation is the desire to achieve very high scalability to handle the vagaries of Internet-size workloads. Yet many big social Web sites (such as Facebook, MySpace, and Twitter) and many other Web sites and distributed tier 1 applications that require high scalability (such as e-commerce and banking) reportedly remain SQL-based for their core data stores and services.
The question is, how do they do it? (SQL is actually the name of a declarative query language, while more precisely this article concerns traditional relational database systems. Since it is common to talk about NoSQL as the opposite of relational database systems, we have taken the editorial liberty of using SQL as a synonym for relational database systems.)