Atomicity and consistency. The classic case is balance transfer. Batch writes only cope with this to the degree that you can model your computation purely in da

Atomicity and consistency. The classic case is balance transfer. Batch writes only cope with this to the degree that you can model your computation purely in database primitives that can execute server-side as part of the batch. If your computation involves anything else, such as external data or a computation that can't be modelled, then microbatches aren't good enough: you risk lost updates and inconsistent reads.