While talking with a client recently about their performance challenges, I was relieved to find that the database wasn't the problem. Instead, their API server was overloaded by the number of calls taking place in their application. While the database did provide the backing for the API calls, there was a fair amount of caching. However, as they'd moved to microservices, more and more of the interaction between modules was taking place as a network call to a single server, which became overloaded.Certainly, they could add more API servers, or break out different types of API servers, but each of these changes potentially has downsides. Data can become out of sync across two systems, which is why we often want a single database storing all data. Distributed systems are hard to architect and implement, and I suspect as more developers try to build them, we'll find more issues like this. Not that developers are doing anything wrong, but they often don't realize the challenges of building a distributed system when the workload scales.

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