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.
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