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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: why does remove need a timestamp?
Date Mon, 09 Nov 2009 16:53:31 GMT
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On Mon, Nov 9, 2009 at 10:46 AM, Ramzi Rabah <rrabah@playdom.com> wrote:
> Makes lots of sense.
> It would be nice to update the API wiki for remove:
> http://wiki.apache.org/cassandra/API
>
> with these details, since the current wording is potentially vague and
> misleading.
>
> Thanks guys
> Ray
>
> On Mon, Nov 9, 2009 at 2:43 AM, Mark Robson <markxr@gmail.com> wrote:
>>
>>
>> 2009/11/9 Ramzi Rabah <rrabah@playdom.com>
>>>
>>> Hello all:
>>> I am confused about the need of passing a  timestamp for the remove
>>> operation. Why does the remove operation in Cassandra require a
>>> timestamp? What happens if I provide a remove call with a different
>>> timestamp than what I inserted, will the row still be deleted?
>>
>> It is so that if the commands are replayed in a different order on different
>> nodes, the same result is produced.
>>
>> Remove only removes values which have a timestamp of before or the same as
>> the one provided - this is essential, as if a "later" insert "overtakes" the
>> remove, the remove needs to avoid removing "newer" data.
>>
>> The eventual consistency model only works (i.e. only produces consistency)
>> if mutations have the same effect regardless of the order they are applied
>> in.
>>
>> That is my understanding anyway.
>>
>> Mark
>>
>

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