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From Kamal Bahadur <>
Subject Re: Consistency Level
Date Tue, 03 Jan 2012 20:44:20 GMT
Hi Peter,

To test, I wiped out all the data from Cassandra and inserted just one
record. The row key is "7a7a32323636373030303438303031". I used
getendpoints to see where my data is and double checked the same using
sstable2json command.

Since the RF is 2, the data is currently on Node 1 and Node 4 of my 4 nodes
cluster. I used cassandra-cli to query the data by using one of the
secondary index but following are my results:

  Test Node 1 Node 2 Node 3 Node 4 Got data back?  1 Up Up Up Up Yes  2 Up
Up Up
Yes  3 Up Up
Up Yes  4
Up Up Up Yes  5 Up Up

No  6

Up Up No  7 Up

Up No

It turns out that even though my consistency level is ONE, since I am using
secondary index to query the data, at least 3 nodes has to be running. And
out of these 3 running nodes, it works even if one nodes contains the data.

Somewhere in the mailing I read that "Iterating through all of the rows
matching an index clause on your cluster is guaranteed to touch N/RF of the
nodes in your cluster, because each node only knows about data that is
indexed locally."

I am not sure what N/RF means in my case. Does it mean 4/2 = 2? where 4 is
the number of nodes and 2 is the RF. If it is 2, why is it not returning
any data when the two nodes that contains the data is running (test #7)?

For my use case, I have to have a RF of 2 and should be able to query using
secondary index with a CL of ONE. Is this possible when 2 nodes are down in
a 4 nodes cluster? Is there any limitations on using secondary index?

Thanks in advance.


On Thu, Dec 29, 2011 at 6:40 PM, Peter Schuller <
> wrote:

> > Thanks for the response Peter! I checked everything and it look good to
> me.
> >
> > I am stuck with this for almost 2 days now. Has anyone had this issue?
> While it is certainly possible that you're running into a bug, it
> seems unlikely to me since it is the kind of bug that would affect
> almost anyone if it is failing with Unavailable due to unrelated (not
> in replica sets) nodes being down.
> Can you please post back with (1) the ring layout ('nodetool ring'),
> and (2) the exact row key that you're testing with?
> You might also want to run with DEBUG level (modify
> at the top) and the strategy (assuming you are
> using NetworkTopologyStrategy) will log selected endpoints, and
> confirm that it's indeed picking endpoints that you think it should
> based on getendpoints.
> --
> / Peter Schuller (@scode,

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