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From aaron morton <aa...@thelastpickle.com>
Subject Re: RE Ordering counters in Cassandra
Date Wed, 23 May 2012 09:42:13 GMT
> Just out of curiosity, is there any underlying architectural reason why it's not possible
to order a row based on its counters values? or is it something that might be in the roadmap
in the future?
it wouldn't work well with the consistency level. 
Also, sorting a list of values at the same time you want multiple clients to be modifying
them would not work very well. 

Cheers

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

On 23/05/2012, at 12:25 AM, samal wrote:

> Secondary index is not supported for counters plus you must know column name to support
secondary index on regular column.
> 
> On 22-May-2012 5:34 PM, "Filippo Diotalevi" <filippo@ntoklo.com> wrote:
> Thanks for all the answers, they definitely helped.
> 
> Just out of curiosity, is there any underlying architectural reason why it's not possible
to order a row based on its counters values? or is it something that might be in the roadmap
in the future?
> 
> -- 
> Filippo Diotalevi
> 
> On Tuesday, 22 May 2012 at 08:48, Romain HARDOUIN wrote:
> 
>> 
>> I mean iterate over each column -- more precisly: *bunches of columns* using slices
-- and write new columns in the inversed index. 
>> Tamar's data model is made for real time analysis. It's maybe overdesigned for a
daily ranking. 
>> I agree with Samal, you should split your data across the space of tokens. Only CF
Ranking feeding would be affected, not the "top N" queries. 
>> 
>> Filippo Diotalevi <filippo@ntoklo.com> a écrit sur 21/05/2012 19:05:28 :
>> 
>> > Hi Romain, 
>> > thanks for your suggestion. 
>> > 
>> > When you say " build every day a ranking in a dedicated CF by 
>> > iterating over events:" do you mean 
>> > - load all the columns for the specified row key 
>> > - iterate over each column, and write a new column in the inversed index 
>> > ? 
>> > 
>> > That's my current approach, but since I have many of these wide rows
>> > (1 per day), the process is extremely slow as it involves moving an 
>> > entire row from Cassandra to client, inverting every column, and 
>> > sending the data back to create the inversed index. 
> 


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