Setting read quorum for map reduce jobs

Johnathan Loggie johnathan.loggie at
Tue May 4 11:20:57 EDT 2010


OK Thanks, I thought as much. Its was more of an academic question really.


On 04/05/2010 15:27, "Sean Cribbs" <sean at> wrote:

> The read quorum doesn't apply to map-reduce - the value from the first vnode
> in the preflist will be tried, followed by the others if it is not available.
> If an input is completely unavailable (as may be the case with 1/2 of the
> nodes down), the job will fail.  2 nodes is a bit of degenerate case anyway -
> especially if you use the default N value of 3.  When the size of the cluster
> smaller than N, there's a chance that some data could become unavailable when
> a node goes down.
> Sean Cribbs <sean at>
> Developer Advocate
> Basho Technologies, Inc.
> On May 4, 2010, at 10:13 AM, Johnathan Loggie wrote:
>> Hi,
>> I¹m struggling to find how to set the the read quorum for a map reduce job
>> via the REST api.
>> The documentation doesn¹t mention that this is even possible.
>> I¹m using ripple, and tried forcing r=1 onto the end of the query string (e.g
>> with @client = = Œ/mapred?r=1¹)) to see if this
>> resource worked like the others, but had no luck.
>> I have 2 riak nodes and have deliberately stopped one as if it were down or
>> disconnected.
>> In this state my map reduce jobs fail to run on the node that is up and
>> running.
>> Can anybody help?
>> Have I completely got the wrong end of the stick on this one?
>> Johnno 
>> _______________________________________________
>> riak-users mailing list
>> riak-users at

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