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https://issues.apache.org/jira/browse/CASSANDRA-2494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13023116#comment-13023116
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Stu Hood edited comment on CASSANDRA-2494 at 4/22/11 6:05 AM:
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W plus R must be _greater than_ N for consistency.
EDIT: And adding a blocking implicit write step to QUORUM reads by waiting for
read repair is not reasonable.
was (Author: stuhood):
W plus R must be _greater than_ N for consistency.
> Quorum reads are not consistent
> -------------------------------
>
> Key: CASSANDRA-2494
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2494
> Project: Cassandra
> Issue Type: Bug
> Reporter: Sean Bridges
>
> 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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