How to create auto increment IDs in Cassandra

Creating a global sequential sequence of number does not really make any sense in a distributed system. Use UUIDs.

(Because you would have to make all participants agree and accept the evolution of the sequence -- under a naive implementation)

There is no good solution.

1. Create a column with a number, increase the number and save it to all replicas together with a temporary id, read all replicas and check if the temporary id is "yours", if not do it again.. not a great solution and will not scale.

or

1. Build your own id service where you fetch your next id. This service will only be run in a single instance and will be a non scaling scary factor.

As soon as anything goes beyond a single instance the sequencing of id's gets complicated, at least if you want it to scale. That includes relational databases.