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From AJ Chen <ajc...@web2express.org>
Subject Re: key is sorted?
Date Sun, 09 May 2010 16:36:55 GMT
just to correct myself: to sort timeUUID on column in descending order,
sliceRange.setReversed(true) does the trick.
-aj

On Sun, May 9, 2010 at 9:07 AM, AJ Chen <ajchen@web2express.org> wrote:

> 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
>



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

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