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From Brian O'Neill <b...@alumni.brown.edu>
Subject Re: CQL3 Compound Primary Keys - Do I have the right idea?
Date Sat, 22 Dec 2012 12:38:36 GMT

Agreed.  I actually flip between cli and cqlsh these days. 

cqlsh shows the logical view.
cli shows the physical view.

This is useful, especially when developing using a thrift-based client.
Here are the slides and video if you want to have a look.

-brian



On Dec 22, 2012, at 3:36 AM, Wz1975 wrote:

> You still add one row. The  column name is the remaining part of the composite key (repeat
for each column) plus each of the column which is not in the composite key. I found it is
much clearer to look at the data through Cassandra -cli which shows you how data is stored.

> 
> 
> Thanks.
> -Wei
> 
> Sent from my Samsung smartphone on AT&T 
> 
> 
> -------- Original message --------
> Subject: CQL3 Compound Primary Keys - Do I have the right idea? 
> From: Adam Venturella <aventurella@gmail.com> 
> To: user@cassandra.apache.org 
> CC: 
> 
> 
> Trying to better grasp compound primary keys and what they are conceptually doing under
the hood. When you create a table with a compound primary key in cql3 (http://www.datastax.com/dev/blog/schema-in-cassandra-1-1)
the first part of the key is the partition key. I get that and the subsequent parts help with
the row name as I understand it.
> 
> So when you add a new row to that columnfamily/table, you are still adding a row. In
other words, the RandomPartitioner places it somewhere in the cluster as a row on it's own
as opposed to just adding a new column to an existing row, which would live on the same node
as the row
> 
> The effect of the compound key means that those rows are effectively treated as if they
were part of the same column, making it a wide column.
> 
> Is that the right idea or do I have the row / rp thing wrong?
> 


Brian ONeill
Lead Architect, Health Market Science (http://healthmarketscience.com)
mobile:215.588.6024
blog: http://weblogs.java.net/blog/boneill42/
blog: http://brianoneill.blogspot.com/


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