Thanks! On Mon, May 10, 2010 at 2:17 PM, Dr. Martin Grabmüller < martin.grabmuel...@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:omalla...@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/ > > -- ............................................................ Olivier Mallassi OCTO Technology ............................................................ 50, Avenue des Champs-Elysées 75008 Paris Mobile: (33) 6 28 70 26 61 Tél: (33) 1 58 56 10 00 Fax: (33) 1 58 56 10 01 http://www.octo.com Octo Talks! http://blog.octo.com
