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From aaron morton <>
Subject Re: Atomicity Strategies
Date Wed, 22 Jun 2011 23:25:18 GMT
Atomic on a single machine yes. 

Aaron Morton
Freelance Cassandra Developer

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
>> I think the issue here is more about atomicity
>> We cannot guarantee that all or none of the mutations in your batch are completed.
There is some work in this area though
> 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!

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