> Is it not possible to include a column in both the set clause and in the > where clause?
No it's not. Or rather in that case what is not supported is the use of secondary indexes in update where clauses. But if 'locked' is indeed not part of your primary key, then at least the error message suck and will need to be improved. Now, why isn't this supported? Honestly I don't remember that we have discussed this much, but I see at least 2 potential reasons why we might hesitate doing it: 1) we won't really be able to implement this in a much better way that you would do client (i.e. by first querying the secondary index and then doing the insertion). In particular, we won't be able to guarantee the atomicity of the read/write involved by such operation. 2) currently writes don't involve read (that isn't true for 2ndary index updates currently but that will be fixed in Cassandra 1.2). That would be a case where a write involves a read, and a fairly costly one. This is not saying this is a bad idea, just that there is more to it than "we've been too lazy to implement it". But if you are interested I encourage you to open a ticket on JIRA to start a discussion. -- Sylvain
