I agree with most of the stuff written in the article (quite a rare thing I must admit :)). But one thing I'd say is a bit outdated: in general whether or not to read from replica is the same decision as whether or not to use caching: it's a (pretty significant) tradeoff. Previously you didn't have much of a choice due to hardware being quite limited. Now, however, you can have literally hundreds of CPU cores, so all those CPUs can very much be busy at work doing reads. Writes obviously do have an overhead, _but_ note that all writes are eventually serialised, _and_ replica needs to handle them as well anyway