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From AJ Chen <ajc...@web2express.org>
Subject Re: key is sorted?
Date Sun, 09 May 2010 16:07:57 GMT
true, i think.
but don't rush to OrderPreservingPartitioners. it may be better to create
another key CF for sorting the key (put the key in column, which is sorted
automatically). to paginate through the records, you get a sorted slice of
keys from the key CF, and then look up the record CF with each key.

One issue i found with the default column sorting is that the timeUUIDType
sorts time-uuid column in ascending order instead of descending order.
get_slice call returns oldest time-uuid instead of most recent time-uuid. Is
this a bug?  normally, you want get_slice returns most recent timeuuid,
which make function like "get most recent 10 records" easy.

-aj

On Sun, May 9, 2010 at 12:00 AM, David Boxenhorn <david@lookin2.com> wrote:

> This is something that I'm not sure that I understand. Can somebody
> confirm/deny that I understand it? Thanks.
>
> If you use random partitioning, you can loop through all keys with a range
> query, but they will not be sorted.
>
> True or False?
>
> On Sat, May 8, 2010 at 3:45 AM, AJ Chen <ajchen@web2express.org> wrote:
>
>> thanks, that works. -aj
>>
>>
>> On Fri, May 7, 2010 at 1:17 PM, Stu Hood <stu.hood@rackspace.com> wrote:
>>
>>> Your IPartitioner implementation decides how the row keys are sorted: see
>>> http://wiki.apache.org/cassandra/StorageConfiguration#Partitioner . You
>>> need to be using one of the OrderPreservingPartitioners if you'd like a
>>> reasonable order for the keys.
>>>
>>> -----Original Message-----
>>> From: "AJ Chen" <ajchen@web2express.org>
>>> Sent: Friday, May 7, 2010 3:10pm
>>> To: user@cassandra.apache.org
>>> Subject: key is sorted?
>>>
>>> I have a super column family for "topic", key being the name of the
>>> topic.
>>> <ColumnFamily Name="Topic" CompareWith="UTF8Type" ColumnType="Super"
>>> CompareSubcolumnsWith="BytesType" />
>>> When I retrieve the rows, the rows are not sorted by the key. Is the row
>>> key
>>> sorted in cassandra by default?
>>>
>>> -aj
>>> --
>>> AJ Chen, PhD
>>> Chair, Semantic Web SIG, sdforum.org
>>> http://web2express.org
>>> twitter @web2express
>>> Palo Alto, CA, USA
>>>
>>>
>>>
>>
>>
>> --
>> AJ Chen, PhD
>> Chair, Semantic Web SIG, sdforum.org
>> http://web2express.org
>> twitter @web2express
>> Palo Alto, CA, USA
>>
>
>


-- 
AJ Chen, PhD
Chair, Semantic Web SIG, sdforum.org
http://web2express.org
twitter @web2express
Palo Alto, CA, USA

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