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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: org.apache.cassandra.service.ReadResponseResolver question
Date Tue, 14 Dec 2010 20:20:26 GMT
Correct.  https://issues.apache.org/jira/browse/CASSANDRA-1830 is open to
fix that.  If you'd like to review the patch there, that would be very
helpful. :)

On Tue, Dec 14, 2010 at 1:55 PM, Daniel Doubleday
<daniel.doubleday@gmx.net>wrote:

> Hi
>
> I'm sorry - don't want to be a pain in the neck with source questions. So
> please just ignore me if this is stupid:
>
> Isn't org.apache.cassandra.service.ReadResponseResolver suposed to throw a
> DigestMismatchException if it receives a digest wich does not match the
> digest of a read message?
>
> If messages contains multiple digest responses it will drop all but one. So
> if any of the dropped digest are a mismatch to the version that mismatch is
> simply ignored.
> It can cope with multiple reads (versions) but not with multiple digests
> and that's what it gets from quorum reads.
>
> It might be an edge case, but I think that would break quorum promise with
> rf > 3 because you could have 1 broken data message, 1 broken digest message
> and 2 good digest messages. If the 2 good messages were dropped than the
> quorum read that should have triggered repair and conflict resolution would
> return old data.
>
> I just can't see what I'm not seeing here.
>
> Cheers,
> Daniel
>
>
>


-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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