I was wondering if it's a good idea to use Cassandra for persist-able circular buffer?

The goal is to have at most X columns per key, where new columns wipe old columns out.
There will be much more writes than reads. What bothers me is how to handle "old" columns.
I understand that there there is no multi-remove, but even if there was that would not help much.

Perhaps Cassandra is ill-suited for the task... What'd you recommend?

It could be done in SQL one way or another but it would be pretty as well:
1. always insert and purge once in a while - this approach fails under any significant load
2. purge on insert - still requires unnecessary reads