Atomic on a single machine yes. ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com
On 23 Jun 2011, at 09:42, AJ wrote: > On 4/9/2011 7:52 PM, aaron morton wrote: >> My understanding of what they did with locking (based on the examples) was >> to achieve a level of transaction isolation >> http://en.wikipedia.org/wiki/Isolation_(database_systems) >> <http://en.wikipedia.org/wiki/Isolation_%28database_systems%29> >> >> I think the issue here is more about atomicity >> http://wiki.apache.org/cassandra/FAQ#batch_mutate_atomic >> >> We cannot guarantee that all or none of the mutations in your batch are >> completed. There is some work in this area though >> https://issues.apache.org/jira/browse/CASSANDRA-1684 >> > > Just to be clear, you are speaking in the general sense, right? The batch > mutate link you provide says that in the case that ALL the mutates of the > batch are for the SAME key (row), then the whole batch is atomic: > > "As a special case, mutations against a single key are atomic but not > isolated." > > So, is it true that if I want to update multiple columns for one key, then it > will be an all or nothing update for the whole batch if using batch update? > But, if your batch mutate containts mutates for more than one key, then all > the updates for one key will be atomic, followed by all the updates for the > next key will be atomic, and so on. Correct? > > Thanks! >
