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From "Aleksey Yeschenko (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-11980) Reads at EACH_QUORUM not respecting the level with read repair or speculative retry active
Date Wed, 08 Jun 2016 15:59:21 GMT
Aleksey Yeschenko created CASSANDRA-11980:
---------------------------------------------

             Summary: Reads at EACH_QUORUM not respecting the level with read repair or speculative
retry active
                 Key: CASSANDRA-11980
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11980
             Project: Cassandra
          Issue Type: Bug
          Components: Coordination
            Reporter: Aleksey Yeschenko


{{ReadCallback::waitingFor()}} is not sophisticated enough to correctly count replies from
replicas towards {{blockFor}}, and can return to the client before getting an actual quorum
in each of the DCs.

Assume DC1: n1, n2, n3; DC2: n4, n5, n6; blockFor in this case would be 4. {{ReadCallback}}
does not count replies from different DCs separately, however, so if the replies return in
order of n1, n2, n3, n4, the request will still succeed, having achieved 4, despite not getting
a quorum from DC2.

The bug potentially manifests itself if RR.GLOBAL, RR.LOCAL, or any speculative retry triggers.

The easiest fix would be to temporarily disable RR and speculative retry on each quorum reads.



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