On Tue, Jun 25, 2013 at 5:30 AM, Blair Zajac <bl...@orcaware.com> wrote:
> But if I want to delete it regardless of v1, then this doesn't work: > > DELETE FROM test WHERE k = 0 IF EXISTS > That's correct, though we should probably fix that at some point. I've opened https://issues.apache.org/jira/browse/CASSANDRA-5708 for that. > So one is left to > > DELETE FROM test WHERE k = 0 > > How does this non-CAS DELETE mix with a CAS UPDATE for the same partition > key? Will they properly not step over each other? > Depends on what you mean by "not step over each other". A CAS update will end up inserting columns with a timestamp that is basically the one of the start of the paxos algorithm use underneath. The delete itself will be a tombstone with a timestamp of when you execute that delete. So the basic rule of "the more recent wins" will apply. Of course if 2 such operations contend, you can't really know which will win. But if you do a delete at QUORUM, followed by a CAS update IF NOT EXISTS (and there is no other concurrently running operation on that row) you are guaranteed that your update will succeed. I don't know if I've answered your question. -- Sylvain > > Thanks, > Blair > > [1] https://github.com/riptano/**cassandra-dtest/blob/master/** > cql_tests.py#L3044<https://github.com/riptano/cassandra-dtest/blob/master/cql_tests.py#L3044> >
