See steps 1-3 in the description section of the issue below:

https://issues.apache.org/jira/browse/CASSANDRA-44

On 4 August 2010 09:27, David Boxenhorn <david@lookin2.com> wrote:
When I change schema I need to delete the commit logs - otherwise I get a null pointer exception.

Is there a way that I can force Cassandra to empty the commit logs so I won't lose data???

(There has not been much recent activity, nor is there much current activity. There was only one log and it was only 54K.)