What characterizes an idempotent operation?

What characterizes an idempotent operation?

• A. It changes results only the first time
• B. It does not change results no matter how often you call
• C. It depends on user authentication
• D. It fails if called twice

Answer: (B)

An idempotent operation yields the same result if you call it once or many times with the same input. After the first invocation, further calls don’t change the state or produce a different outcome. This property is crucial for reliability in distributed systems because retries caused by failures should not create duplicates or alter results. Think of setting a value to a specific constant: no matter how many times you perform that action with the same value, the final state remains the same. In many APIs, such as updating a resource to a fixed state, repeated calls are safe because the end result is unchanged. So the best description is that the operation does not change results no matter how often you call it. The other ideas imply changes on subsequent calls or rely on factors like authentication, which aren’t what defines idempotence.

An idempotent operation yields the same result if you call it once or many times with the same input. After the first invocation, further calls don’t change the state or produce a different outcome. This property is crucial for reliability in distributed systems because retries caused by failures should not create duplicates or alter results.

Think of setting a value to a specific constant: no matter how many times you perform that action with the same value, the final state remains the same. In many APIs, such as updating a resource to a fixed state, repeated calls are safe because the end result is unchanged.

So the best description is that the operation does not change results no matter how often you call it. The other ideas imply changes on subsequent calls or rely on factors like authentication, which aren’t what defines idempotence.