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From aaron morton <aa...@thelastpickle.com>
Subject Re: About Composite range queries
Date Thu, 31 May 2012 10:09:29 GMT
it is hashed once. 

To the partitioner it's just some bytes. Other parts of the code car about it's structure.


Cheers

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 31/05/2012, at 7:00 PM, Cyril Auburtin wrote:

> Thx for the answer
> 1 more thing, a Composite key is not hashed only once I guess?
> It's hashed the number of part the composite have?
> So this means there are twice or 3 or ... as many keys as for normal column keys, is
it true?
> 
> Le 31 mai 2012 02:59, "aaron morton" <aaron@thelastpickle.com> a écrit :
> Composite Columns compare each part in turn, so the values are ordered as you've shown
them. 
> 
> However the rows are not ordered according to key value. They are ordered using the random
token generated by the partitioner see http://wiki.apache.org/cassandra/FAQ#range_rp
> 
>> What is the real advantage compared to super column families?
> They are faster. 
> 
> Cheers
> 
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
> 
> On 29/05/2012, at 10:08 PM, Cyril Auburtin wrote:
> 
>> How is it done in Cassandra to be able to range query on a composite key?
>> 
>> "key1" => (A:A:C), (A:B:C), (A:C:C), (A:D:C), (B,A,C)
>> 
>> like get_range ("key1", start_column=(A,"), end_column=(A, C)); will return [ (A:B:C),
(A:C:C) ] (in pycassa)
>> 
>> I mean does the composite implementation add much overhead to make it work?
>> Does it need to add other Column families, to be able to range query between composites
simple keys (first, second and third part of the composite)?
>> 
>> What is the real advantage compared to super column families?
>> 
>> "key1" => A: (A,C), (B,C), (C,C), (D,C)  , B: (A,C)
>> 
>> thx
> 


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