There is nothing in the 0.8 trunk to add double support.
Could you shift the decimal point and use ints / longs ? Double is not a
precise type, so there is a possibility of the value changing as it's
serialised and deserialised around.
You were on the right track with extending abstract type. You would also need
to work out a precise binary representation for the numbers.
Hope that helps.
Aaron
On 14 Mar 2011, at 13:36, Paul Teasdale 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
>
>
>
>
>
>
>
