To ensure consistency, serverless computing functions should be idempotent.
Mathematically, a function is idempotent if, whenever it is applied twice to any value, it gives the same result as if it were applied once, that is, ƒ(ƒ(x)) ≡ ƒ(x).
To give a simple example of a non-idempotent function, imagine a function with a task of calculating a square root of the input number. If the function is run a second time on an input value that has already been processed, it will result in an incorrect output, as √(√(x)) ≠ √(x). Thus, the only way to ensure that the function remains idempotent is making sure that the same input isn't processed twice.
In an asynchronous, highly parallelized environment ran by ephemeral compute ...
