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From Olivier Mallassi <omalla...@octo.com>
Subject Re: trying to make my ideas clear about partionning...
Date Mon, 10 May 2010 12:25:24 GMT
Thanks!

On Mon, May 10, 2010 at 2:17 PM, Dr. Martin Grabmüller <
Martin.Grabmueller@eleven.de> wrote:

>  Partitioning is only done for row keys,  the part in your message about
> keys and partitioning is correct.
> There is no partitioning for columns, all columns for a particular key are
> stored on the same node (plus
> replicas, of course, which are stored on different nodes).  The CompareWith
> option for column families
> only affects the ordering of columns/supercolumns, not the partitioning.
>
> Cheers,
>   Martin
>
>  ------------------------------
> *From:* Olivier Mallassi [mailto:omallassi@octo.com]
> *Sent:* Monday, May 10, 2010 1:17 PM
> *To:* user@cassandra.apache.org
> *Subject:* trying to make my ideas clear about partionning...
>
> Hi all,
>
> I am trying to make my ideas clear about how the partioning works in
> Cassandra.
>
> Here is what I understood, pease correct me if I am wrong.
>
> - Row key are partitionned based on the partitionning strategy you choose
> (randon, order preserving, custom if you implemented the IPartioner
> interface). One partionning strategy is defined per cluster (in fact for
> each node of the cluster but the confifguration should be the sames so...)
> Order Preserving Partionning is better for range queries because the key
> are stored in a sequential way so when selecting a range of keys, you hit
> less nodes than with the RandomPartitioner.
>
> - Once this first partitioning is done, a second one is done based on the
> Column (or SuperColumn) name and the CompareWith you defined for the
> ColumnFamily.
>
> Am I right?
> Am I wrong if I say that potentially the different columns of the same
> ColumnFamily are stored on different nodes? So if I wanna read a complete
> row, I hit several nodes.
> Is there a way of controlling the way Column are stored?
>
> Thanks for your help.
>
> Oliv/
>
>


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Olivier Mallassi
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