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Posted to commits@cassandra.apache.org by "Aaron Brown (JIRA)" <ji...@apache.org> on 2015/09/24 22:46:04 UTC
[jira] [Commented] (CASSANDRA-2494) Quorum reads are not
monotonically consistent
[ https://issues.apache.org/jira/browse/CASSANDRA-2494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14906978#comment-14906978 ]
Aaron Brown commented on CASSANDRA-2494:
----------------------------------------
The relevant code in the patch has changed significantly. Is the monotonic read consistency guarantee still provided?
> Quorum reads are not monotonically consistent
> ---------------------------------------------
>
> Key: CASSANDRA-2494
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2494
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Sean Bridges
> Assignee: Jonathan Ellis
> Priority: Minor
> Fix For: 1.0.0
>
> Attachments: 2494-v2.txt, 2494.txt
>
>
> As discussed in this thread,
> http://www.mail-archive.com/user@cassandra.apache.org/msg12421.html
> Quorum reads should be consistent. Assume we have a cluster of 3 nodes (X,Y,Z) and a replication factor of 3. If a write of N is committed to X, but not Y and Z, then a read from X should not return N unless the read is committed to at least two nodes. To ensure this, a read from X should wait for an ack of the read repair write from either Y or Z before returning.
> Are there system tests for cassandra? If so, there should be a test similar to the original post in the email thread. One thread should write 1,2,3... at consistency level ONE. Another thread should read at consistency level QUORUM from a random host, and verify that each read is >= the last read.
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