-**You have a high-throughput function and want to reduce cost.** When you define a batch handler, Segment invokes the function once per*batch*, rather than once per event. As long as the function’s execution time isn’t adversely affected, the reduction in invocations should lead to a reduction in cost.

-**Your destination supports batching**. When your downstream destination supports sending data downstream in batches you can define a batch handler to avoid throttling. Batching for functions is independent of batch size supported by the destination. Segment automatically handles batch formation for destinations internally.

-**Your destination supports batching**. When your downstream destination supports sending data downstream in batches you can define a batch handler to avoid throttling. Batching for functions is independent of batch size supported by the destination. Segment automatically handles batch formation for destinations.