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From Theo Hultberg <t...@iconara.net>
Subject Re: [Cassandra] Conflict resolution in Cassandra
Date Fri, 07 Jun 2013 15:54:06 GMT
Like Edward says Cassandra's conflict resolution strategy is LWW (last
write wins). This may seem simplistic, but Cassandra's Big Query-esque data
model makes it less of an issue than in a pure key/value-store like Riak,
for example. When all you have is an opaque value for a key you want to be
able to do things like keeping conflicting writes so that you can resolve
them later. Since Cassandra's rows aren't opaque, but more like a sorted
map LWW is almost always enough. With Cassandra you can add new
columns/cells to a row from multiple clients without having to worry about
conflicts. It's only when multiple clients write to the same column/cell
that there is an issue, but in that case you usually can (and you probably
should) model your way around that.

T#


On Fri, Jun 7, 2013 at 4:51 PM, Edward Capriolo <edlinuxguru@gmail.com>wrote:

> Conflicts are managed at the column level.
> 1) If two columns have the same name the column with the highest timestamp
> wins.
> 2) If two columns have the same column name and the same timestamp the
> value of the column is compared and the highest* wins.
>
> Someone correct me if I am wrong about the *. I know the algorithm is
> deterministic, I do not remember if it is highest or lowest.
>
>
> On Thu, Jun 6, 2013 at 6:25 PM, Emalayan Vairavanathan <
> svemalayan@yahoo.com> wrote:
>
>> I tried google and found conflicting answers. Thats why wanted to double
>> check with user forum.
>>
>> Thanks
>>
>>   ------------------------------
>>  *From:* Bryan Talbot <btalbot@aeriagames.com>
>> *To:* user@cassandra.apache.org; Emalayan Vairavanathan <
>> svemalayan@yahoo.com>
>> *Sent:* Thursday, 6 June 2013 3:19 PM
>> *Subject:* Re: [Cassandra] Conflict resolution in Cassandra
>>
>> For generic questions like this, google is your friend:
>> http://lmgtfy.com/?q=cassandra+conflict+resolution
>>
>> -Bryan
>>
>>
>> On Thu, Jun 6, 2013 at 11:23 AM, Emalayan Vairavanathan <
>> svemalayan@yahoo.com> wrote:
>>
>> Hi All,
>>
>> Can someone tell me about the conflict resolution mechanisms provided by
>> Cassandra?
>>
>> More specifically does Cassandra provides a way to define application
>> specific conflict resolution mechanisms (per row basis  / column basis)?
>>            or
>> Does it automatically manage the conflicts based on some synchronization
>> algorithms ?
>>
>>
>> Thank you
>> Emalayan
>>
>>
>>
>>
>>
>>
>

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