Re: composite column for primary key in cluster

[Mikael Ronström]

Composite primary keys are ok to use. The overhead is mainly in that you need to communicate the entire primary key (up to 60 bytes in your case) for each key lookup for updates, inserts and keyed reads. A smaller key means less bytes in the primary key to send over to the data node. Apart from that the execution inside the data node is almost as quick, it has to transport a bit more data internally but not drastically much more.

So it is an optimisation to use short primary keys, but then I gather that composite keys have other advantages in your case that might still make it
worthwhile to use them.