Nothing scales indefinitely, not even RoR. But that wasn't what the article complained about. If the author had written "SQL Databases Don't Scale Indefinitely"

Nothing scales indefinitely, not even RoR. But that wasn't what the article complained about. If the author had written "SQL Databases Don't Scale Indefinitely" I wouldn't have any complaint about it. My point is that there are plenty of real-world examples of SQL databases that are scaled way beyond any RoR web app's needs, so flatly claiming they don't scale is wrong. The solution banks (and other large organizations) have arrived at -- using multiple databases with different transactional and availability requirements -- IS a solution to scaling large databases. There's no requirement that SQL databases be monolithic. Even the original article describes using a MySQL master for updates and one or more slaves for reads. That's a valid scalability solution if your application can live with the possibility of stale data in the slaves.