There’re many instances where you need scalable, globally persistent counter. Most popular use cases are when you need a monotonically increasing number. Coinbase APIs for e.g. have such a requirement. Alternatively, maybe you want to assign a unique id to your users or your responses, without the single table and global lock limitations of a MySQL instance, which can be quite slow.

This API uses sharding, and ensures that before the call returns, the shard has been successfully persisted. This way, when never loose an applied delta, in other words, your counter doesn’t jump back.