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From Benjamin Black...@b3k.us>
Subject Re: Write consistency
Date Thu, 08 Apr 2010 16:46:46 GMT
His arguments consistently (hah!) boil down to this: if you
misconfigure things for your intended application, you get undesirable
behavior.  For example, the correct approach to the situation cited is
to use quorum reads and writes.  W=3/R=1/N=3 might be appropriate for
situations in which you want to force writes to a remote datacenter
(using appropriate placement strategy), but are not concerned with
clients always seeing the same data at any given instant.


b

On Thu, Apr 8, 2010 at 12:55 AM, Paul Prescod <paul@ayogo.com> wrote:
> In this¹ debate, there seemed to be consensus on the following fact:
>
> "In Cassandra, say you use N=3, W=3 & R=1. Let’s say you managed to
> only write to replicas A & B, but not C. In this case Cassandra will
> return an error to the application saying the write failed- which is
> acceptable given than W=3. But Cassandra does not cleanup/rollback the
> writes that happened to A & B."
>
> If this is still true (even for ConsistencyLevel.ALL) then I would
> like to add it to the API documentation. I'd also be curious about if
> there have been discussions about for an optional 2PC mode for use on
> fast LANs.
>
>  Paul Prescod
>
> ¹ http://jsensarma.com/blog/2009/11/dynamo-part-i-a-followup-and-re-rebuttals/
>

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