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From "Pamecha, Abhishek" <apame...@x.com>
Subject Re: sorting by value
Date Fri, 31 Aug 2012 07:34:43 GMT
Thanks St.Ack and Tom.  Yes I too kinda came up with a similar scheme -- To store the rank
as part of the key. Where it broke down for me was for say, k-dimensional   data where ranks
are stored for dimension A but the query requires sorting by dimension b. 

For now I have to settle with predetermined dimensions on which to sort. Whereas my ideal
requirement is to pick top-N of  all points in an arbitrary hyper plane in a k - dimensional
space. 

Thanks
Abhishek


i Sent from my iPad with iMstakes 

On Aug 30, 2012, at 23:14, "Tom Brown" <tombrown52@gmail.com> wrote:

> We do numerical sorting within some of our tables.  We put the numerical
> values as fixed length byte arrays within the keys (and flipped the sign
> bit so negative values are lexigraphically lower than positive values)
> 
> Of course, it's still part of the key so that technique doesn't work for
> everyone, but it does allow us to do some limited sorting.
> 
> --Tom
> 
> On Thursday, August 30, 2012, Stack wrote:
> 
>> On Tue, Aug 28, 2012 at 4:11 PM, Pamecha, Abhishek <apamecha@x.com<javascript:;>>
>> wrote:
>>> Hi
>>> 
>>> I probably know the usual answer but are there any tricks to do some
>> sort of sort by value in HBase. The only option I know is to somehow embed
>> value in the key part. The value is not a timestamp but a normal number.
>>> 
>>> I want to find out, say, top 10 from a range of columns. The range could
>> be millions of columns. The range is dynamic for the most part.
>>> 
>>> Any pointers?
>>> 
>> 
>> 
>> HBase sorts by rows and then within a row by column family, column
>> qualifier, type, then timestamp.  You cannot have it natively sort
>> values for you, not unless you make the values be rows and/or columns
>> in another, separate table.
>> 
>> St.Ack
>> 

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