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From Benjamin Black...@b3k.us>
Subject Re: batch_mutate atomicity
Date Sat, 07 Aug 2010 18:04:42 GMT
The first.

On Sat, Aug 7, 2010 at 10:04 AM, james anderson <james.anderson@setf.de> wrote:
> good afternoon;
>
> On 2010-08-07, at 15:26 , Jonathan Ellis wrote:
>
>> I am using the familiar meanings from ACID:
>>
>> atomic means either the entire update will succeed or none of it.
>>
>> isolated means other threads will not see partial updates while it is
>> being applied.
>
> yes, those terms are not new.
>
> it remains, that the answer with respect to isolation would be clearer were
> it expressed in terms of cassandra's operations. given the two-level map
> passed to batch_mutate,
>
> is it that another thread could see the effect of some mutation object in
> one entry of the inner key map, but not see the effect of some other
> mutation object in the same entry of the inner key map?
>
> or
>
> is it that another thread could see the effect of one set of mutation
> objects in one entry of the inner key map, but not see the effect of some
> other set of mutation object in a different entry of the inner key map?
>
> which one?
>
>>
>> On Sat, Aug 7, 2010 at 12:50 AM, james anderson <james.anderson@setf.de>
>> wrote:
>>>
>>> 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
>>>
>>>
>>
>>
>>
>> --
>> Jonathan Ellis
>> Project Chair, Apache Cassandra
>> co-founder of Riptano, the source for professional Cassandra support
>> http://riptano.com
>
>

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