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From "Duncan Sands (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6600) Huge read latency with LOCAL_ONE when < RF nodes are up
Date Fri, 17 Jan 2014 15:23:21 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13874851#comment-13874851
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Duncan Sands commented on CASSANDRA-6600:
-----------------------------------------

The cqlsh testing procedure is incorrect (sorry for the mistake), so for the moment I can't
eliminate the possibility that the problem is in the client.  I will try to reduce the problem
to something reproducible over the next few days.

> Huge read latency with LOCAL_ONE when < RF nodes are up
> -------------------------------------------------------
>
>                 Key: CASSANDRA-6600
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6600
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Duncan Sands
>            Assignee: Michael Shuler
>
> I recently upgraded a multi data centre cluster from 1.2.12 to 2.0.4.
> In one data centre there are 3 nodes with an RF of 3.  Clients are reading from these
nodes using CQL3 and LOCAL_ONE.  At one point during the upgrade 1 node was down, so less
than RF nodes were up.  Read latency went from < 1ms to > 1 second.  Once all nodes
were up, read latency went back down to < 1ms.  If I stop a node then read latency shoots
back up again.
> This is not due to my client as I was able to reproduce this as follows.  With all RF
nodes up:
>   connect to a node using cqlsh
>   set the consistency level to LOCAL_ONE
>   use cqlsh to read a few values from a random table - it completes instantly
>   bring down one of the other nodes in the same data centre
>   do the same query again in cqlsh.  It times out with "Request did not complete within
rpc_timeout".



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