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From james anderson <james.ander...@setf.de>
Subject Re: batch_mutate atomicity
Date Sat, 07 Aug 2010 04:50:31 GMT
good morning;

On 2010-08-07, at 02:45 , Jonathan Ellis wrote:

> Everything in the same key of a batch_mutate is atomic.  (But not  
> isolated.)
>

what does the distinction mean in the context of cassandra?
is it that the execution of an operation with the same key could see  
the effect of the 'first' mutation on one column family but not  
another, or that they could see the presence/absence of some columns  
in a row, but not others, or?

would it be possible to illustrate the difference with some simple  
examples.

> On Fri, Aug 6, 2010 at 2:15 PM, B. Todd Burruss <bburruss@real.com>  
> wrote:
>> ok i just saw the FAQ
>> (http://wiki.apache.org/cassandra/FAQ#batch_mutate_atomic)
>>
>> follow up question ...
>>
>> it states that "As a special case, mutations against a single key are
>> atomic, but more generally no" ... i interpret that to also mean " ..
>> mutations against a single key in the same CF ... "
>>
>> so if i have several mutatations against a single key, but multiple
>> column families i assume this is not atomic?
>>
>> thx
>>
>>
>> On Fri, 2010-08-06 at 11:08 -0700, Todd Burruss wrote:
>>> if i am using batch_mutate to update/insert two columns in the  
>>> same CF
>>> and same key, is this an atomic operation?
>>>
>>> i understand that an operation on a single key in a CF is atomic,  
>>> but
>>> not sure if the above scenario boils down to two operations or
>>> considered one operation.
>>>
>>> thx
>>>
>>
>>
>>
>
>
>
> -- 
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com


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