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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Double ColumnType and comparing
Date Mon, 14 Mar 2011 13:40:38 GMT
We'd be happy to commit a patch contributing a DoubleType.

On Sun, Mar 13, 2011 at 7:36 PM, Paul Teasdale <teasdalep@gmail.com> wrote:
> I am quite new to Cassandra and am trying to model a simple Column Family
> which uses Doubles as column names:
> Datalines: { // ColumnFamilly
> dataline-1:{ // row key
> 23.5: 'someValue',
> 23.6: 'someValue',
> ...
>                4334.99: 'someValue'
> },
> dataline-2:{
> 10.5: 'someValue',
> 12.6: 'someValue',
> ...
>                23334.99: 'someValue'
> },
> ...
> dataline-n:{
> 10.5: 'someValue',
> 12.6: 'someValue',
> ...
>                23334.99: 'someValue'
>           }
> }
> In declaring this column family, I need to specify a 'CompareWith' attribute
> for a Double type, but the only available values I found for this attribute
> are:
>  * BytesType
>  * AsciiType
>  * UTF8Type
>  * LongType
>  * LexicalUUIDType
>  * TimeUUIDType
> Is there any support anywere for double values (there has to be something)?
> And if not, does this mean we need to extend
>  org.apache.cassandra.db.marshal.AbstractType<Double>?
> package  com.mycom.types;
> class  DoubleType extends
> org.apache.cassandra.db.marshal.AbstractType<Double> {
>      public int compare(ByteBuffer o1, ByteBuffer o2){
>        // trivial implementation
>            Double d1  = o1.getDouble(0);
>   Double d2 = o2.getDoube(0);
>   return d1.compareTo(d2);
>      }
>      //...
> }
> And declare the column family:
> <ColumnFamily CompareWith="<com.mycom.types.DoubleType>" Name="Datalines"/>
> Thanks,
> Paul
>
>
>
>
>
>
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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