incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From AJ ...@dude.podzone.net>
Subject Re: Atomicity Strategies
Date Wed, 22 Jun 2011 23:39:06 GMT
Thanks Aaron!

On 6/22/2011 5:25 PM, aaron morton wrote:
> 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!
>>
>


Mime
View raw message