An SNS topic fans citywide alerts, but the parks department Lambda should only process messages tagged department=parks. How should invocations be reduced?
Select an answer to reveal the explanation.
Short Explanation
Don't wake every department Lambda for every citywide shout. Put a subscription filter on SNS so parks only gets department=parks. Fewer useless invokes, happier parks code.
Full Explanation
Amazon SNS subscription filter policies deliver only matching messages to a subscriber, reducing unnecessary Lambda invocations. Filtering after every function wakes, hard-coding alerts, or raising concurrency to absorb noise wastes compute. Filter policies are the standard way to narrow fan-out for departmental consumers.