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From aaron morton <aa...@thelastpickle.com>
Subject Re: rangeQuery to traverse keys backward?
Date Sat, 02 Feb 2013 07:06:43 GMT
There is no facility to do a get_range in reverse. 

Rows are ordered by their token, and using the Random or Murmur3 partitioner this means they
are randomly ordered. So there is not much need to go backwards, or get 10 rows from either
side of a particular row. 

Can you change your data model to not require precise range scans ? 

Cheers

-----------------
Aaron Morton
Freelance Cassandra Developer
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 1/02/2013, at 1:36 PM, Yuhan Zhang <yzhang@onescreen.com> wrote:

> Hi all,
> 
> I'm tryinng to use get_range to traverse the rows by page by providing a :start_key and
an :finish_key.
> 
> This works fine when I traverse forward with :start_key=>last_key, :finish_key=>""
> However, when I tried to traversed backward with :start_key="", :finish_key=>first_key,
this always gave me the first few rows in the column family.
> (my goal is to get  the rows adjacent to my "first_key")
> 
> looks like it always takes priority of :start_key over the :finish_key.
> 
> as for column range,  there is an option to reverse the order. but there is an option
for  traversing rows.
> so I'm wondering whether cassandra is capable of doing this task with the current api
> 
> I tried both twitter cassandra client and hector client, but couldn't find a way to perform
it.
> have someone been able to do this?
> 
> 
> Thank you
> 
> Yuhan 
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