Knowledge MaxxingIdempotency
Idempotency is a property of an operation where running it multiple times has the same effect as running it once, even if it's accidentally repeated.
Prerequisite: Message queue
What matters
In distributed systems, messages or requests can sometimes be delivered more than once; idempotent operations make that safe, since repeating them doesn't cause duplicate side effects.
Example
An operation that sets 'status = paid' is idempotent, since running it twice leaves the same result, unlike an operation that increments a counter by one each time it runs.
Common misconception
Idempotency does not mean an operation can only be run once; it means running it more than once causes no additional unwanted effect beyond the first time.
Recall question
Why does idempotency matter for operations in a system where messages can be delivered more than once?