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Idempotence in Distributed Systems

Sooner or later, you will come across the term “idempotence” in the context of distributed systems. What is the relationship between these terms?

Let’s consider writing an REST API with a POST request. When you try to create a resource and call it multiple times, the system should only create this resource once, or update it, for a given unique entity.

A more specific example of this in a distributed system could be a payment system. A payment operation will be considered idempotent if we attempt to apply the same charge or payment multiple times, but it only gets processed once.

Creating idempotent operations in a distributed system can be challenging, especially if implemented in the application layer. If possible, you can push this responsibility to your database and ensure idempotence with features like unique indices.

This is what I’ve been learning and I’m excited to learn more!