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From Jérôme Verstrynge <jvers...@gmail.com>
Subject Re: What happens if there is a collision?
Date Thu, 21 Oct 2010 03:15:26 GMT
On 21/10/2010 4:43, Jonathan Ellis wrote:
> On Wed, Oct 20, 2010 at 8:38 PM, Jérôme Verstrynge<jverstry@gmail.com>  wrote:
>> -) Let's imagine node A updates MyColumn with value 'AAA' and timestamp
>> 3567890
>> -) Let's imagine node E updates MyColumn with value 'EEE' and timestamp
>> 3567890
>>
>> What happens? Who wins? Is it deterministic?
> value breaks ties if timestamps are identical, so AAA would win.
OK. Thanks for your quick answer.

>> Let's imagine node A performs 3 writes before node E, is any node notified
>> of the collision?
> I don't understand the question.
If there is a timestamp tie, then 'AAA' wins. So node E's call to 
Cassandra's write method will return without being performed, because 
node A's 'AAA' won the timestamp tie.

My question is: is node E notified that it lost the battle against A? If 
yes how?

If not, then it means that, although writes are atomic, they would not 
be deterministic. Node E would have to verify that its write was 
successful...

Jérôme


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