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From Dave Brosius <dbros...@mebigfatguy.com>
Subject Re: RandomPartitioner is providing a very skewed distribution of keys across a 5-node Solandra cluster
Date Sun, 24 Jun 2012 17:38:31 GMT
If i read what you are saying, you are _not_ using composite keys? 
That's one thing that could do it, if the first part of the composite 
key had a very very low cardinality.

On 06/24/2012 11:00 AM, Safdar Kureishy wrote:
> Hi,
>
> I've searched online but was unable to find any leads for the problem 
> below. This mailing list seemed the most appropriate place. Apologies 
> in advance if that isn't the case.
>
> I'm running a 5-node Solandra cluster (Solr + Cassandra). I've setup 
> the nodes with tokens /evenly distributed across the token space/, for 
> a 5-node cluster (as evidenced below under the "effective-ownership" 
> column of the "nodetool ring" output). My data is a set of a few 
> million crawled web pages, crawled using Nutch, and also indexed using 
> the "solrindex" command available through Nutch. AFAIK, the key for 
> each document generated from the crawled data is the URL.
>
> Based on the "load" values for the nodes below, despite adding about 3 
> million web pages to this index via the HTTP Rest API (e.g.: 
> http://9.9.9.x:8983/solandra/index/update....), some nodes are still 
> "empty". Specifically, nodes 9.9.9.1 and 9.9.9.3 have just a few 
> kilobytes (shown in *bold* below) of the index, while the remaining 3 
> nodes are consistently getting hammered by all the data. If the 
> RandomPartioner (which is what I'm using for this cluster) is supposed 
> to achieve an even distribution of keys across the token space, why is 
> it that the data below is skewed in this fashion? Literally, no key 
> was yet been hashed to the nodes 9.9.9.1 and 9.9.9.3 below. Could 
> someone possibly shed some light on this absurdity?.
>
> [me@hm1 solandra-app]$ bin/nodetool -h hm1 ring
> Address         DC          Rack        Status State   Load           
>  Effective-Owership  Token
>                                                                       
>                      136112946768375385385349842972707284580
> 9.9.9.0       datacenter1 rack1       Up     Normal  7.57 GB         
> 20.00%              0
> 9.9.9.1       datacenter1 rack1       Up     Normal *21.44 KB*       
>  20.00%              34028236692093846346337460743176821145
> 9.9.9.2       datacenter1 rack1       Up     Normal  14.99 GB       
>  20.00%              68056473384187692692674921486353642290
> 9.9.9.3       datacenter1 rack1       Up     Normal *50.79 KB*       
>  20.00%              102084710076281539039012382229530463435
> 9.9.9.4       datacenter1 rack1       Up     Normal  15.22 GB       
>  20.00%              136112946768375385385349842972707284580
>
> Thanks in advance.
>
> Regards,
> Safdar


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