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From Alex Dong <alex.d...@binaryplex.com>
Subject Re: Possible to do sort...limit on Cassandra?
Date Mon, 18 Jan 2010 05:19:58 GMT
Thanks Jonathan,

> two, if you use OrderPreservingPartitioner (whcih lets you specify key
> sort order)
I guess this is still a rather static approach, right?
That is, if I use a specified OrderPreservingPartitioner, I will be  
locked into the physical data layout specified here.
Or, am I missing anything?

According to the BigTable paper, the 'rows' are ordered by PK but you  
still have the flexibility to create index on 'Column' or  
'ColumnFamily'.  Do we have similar mechanism in Cassandra?

Thanks,
Alex

On 2010-1-18, at 下午3:28, Jonathan Ellis wrote:

> you get one "sort" for free, which is the column sort you specify with
> CompareWith
>
> two, if you use OrderPreservingPartitioner (whcih lets you specify key
> sort order)
>
> On Sun, Jan 17, 2010 at 5:18 PM, Alex Dong  
> <alex.dong@binaryplex.com> wrote:
>> Hi folks,
>>
>> I'm new to Cassandra.  I'm evaluating Cassandra, HBase and  
>> Voldemort to see
>> which one matches our app model better. Here is a typical data model:
>>
>> stats {
>>        word_id: {
>>                user_id: {
>>                        total_hits: 193,
>>                        monthly_hits: [2, 31, 21, 10, 10, 7, 8, 0,  
>> 0, 0, 1,
>> 2]
>>                },
>>                ..
>>        }
>>        ...
>> }
>>
>> I'm sure that I can pull all the data out from Cassandra and use  
>> mapreduce
>> to sort or merge.   But I'm wondering are there any way in  
>> cassandra to
>> 'automate' this process:
>> 1) for a given 'word_id', get a list of user_id: { }  sorted by
>> 'total_hits'?
>> 2) for two 'word_id's, get an 'intersect' result of the user: {}  
>> list sorted
>> by the combined 'total_hits'?
>>
>> Cheers,
>> Alex
>>

-----------------------------------------------------
Alex Dong
Co-Founder BinaryPlex
http://binaryplex.com/
twitter: @alexdong


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