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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: An ORM like plugin for Cassandra under Datanucleus
Date Sat, 22 May 2010 01:07:34 GMT
Thanks!

You should probably add it to http://wiki.apache.org/cassandra/ClientOptions.

On Fri, May 21, 2010 at 12:22 PM, Pedro Gomes
<pedrogomes@lsd.di.uminho.pt> wrote:
> Hi all
> In the following weeks I have developed a plugin to the java persistence
> platform Datanucleus, similar to the one presented by Google for App Engine
> and a Hbase already present in the platform .
> Datanucleus: http://www.datanucleus.org/project/download.html
> For now it allows the persistence of simples fields and one-one, one-many,
> and many-many relations, supporting collections and maps, arrays are next
> through the Java Data Objects (JDO) API.
> The platform allows a query language JDOQL, but I didn't add the support for
> it.
> You can access the project under :
> http://github.com/PedroGomes/datanucleus-cassandra
> Any feedback or doubts are welcome.
> I still have, though, some doubts on the implementation. To store many-many,
> and one to many relations in Cassandra, i.e., one collection/map of pointers
> to other objects I see two options:
> -The column, in the Column family class, correspondent to the relation
> contains a collection or map that codes the relation, i.e. it stores the ids
> to the objects,. This can be dangerous if the collection/map grows large.
> -You have a column family that codes relations, one simple Column family per
> relation, or a Super Column family that codes all relations . This approach
> however,  makes each fetch from the collection takes 3 read steps, but each
> object id is stored separately.
> Other option that I'm thinking is a hybrid solution where the user chooses
> the pretended option.
> If someone can give some advice on this, I would be thankful.
> Grateful
> Pedro Gomes
>
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-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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