Maybe we could create deleteRequest before the for loop? And inside of that loop, we could just change the message id. That would result in a lot fewer allocations, right?

Curious for your perspective

There is a reason why I've put it inside the loop and we re-create it every loop:
If we have the Aws::DynamoDB::Model::DeleteRequest deleteRequest outside of the loop and then use deleteRequest.AddKey(...) inside the loop we will always delete only the first key-value because AddKey(...) uses emplace to populate an inner map. In this case, the only first kay-value pair will be inserted because emplace will ignore the next key inserts (because the key already exists in the map from the previous loop).

We can possibly use it outside of the loop if we have the ability to clear the inner map, but SDK doesn't have a such method.

In another way, we can use SetKey(...) instead of AddKey(...), but this changes don't provide any improvement in this case.