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From Shaun Cutts <sh...@cuttshome.net>
Subject Re: Finding the intersection results of column sets of two rows
Date Sun, 06 Feb 2011 22:23:00 GMT
In theory, you should be able to do joins by creating an extra column in one column family,
holding the "foreign key" of the matching row in the other family.

This assumes that the info you are joining on is available in both CFs (is not some sort of
functional transformation). 

I have just found that the implementation for secondary indexes is not yet very close to optimal
for more complex "joins" involving multiple indexes, I'm not sure if that affects you as you
didn't say what you are joining on.

-- Shaun


On Feb 6, 2011, at 4:22 PM, Aaron Morton wrote:

> Is it possible for you to dernormalise and write all the intersection values? Will depend
on how many I guess. 
> 
> The other alternative is to pull back more data that you need and the intersection in
code in the client. 
> 
> 
> Hope that helps.
> Aaron
> On 7/02/2011, at 7:11 AM, Aklin_81 <asdkl93@gmail.com> wrote:
> 
>> Hi,
>> 
>> @buddhasystem : yes that's well known solution. But obviously when
>> mysql couldnt satisfy my needs, I am here. My question is in context
>> of Cassandra, if it possible to achieve intersection result set of
>> columns in two rows, by the way I spoke about.
>> 
>> @Edward: yes that I know but how does that fit here for obtaining the
>> common columns among two rows.
>> 
>> Thanks for your comments..
>> 
>> -Asil
>> 
>> 
>> On Sun, Feb 6, 2011 at 9:55 PM, Edward Capriolo <edlinuxguru@gmail.com> wrote:
>>> On Sun, Feb 6, 2011 at 10:15 AM, buddhasystem <potekhin@bnl.gov> wrote:
>>>> 
>>>> Hello,
>>>> 
>>>> If the amount of data is _that_ small, you'll have a much easier life with
>>>> MySQL, which supports the "join" procedure -- because that's exactly what
>>>> you want to achieve.
>>>> 
>>>> 
>>>> asil klin wrote:
>>>>> 
>>>>> Hi all,
>>>>> 
>>>>> I want to procure the intersection of columns set of two rows (from 2
>>>>> different column families).
>>>>> 
>>>>> To achieve the intersection results, Can I, first retrieve all
>>>>> columns(around 300) from first row and just query by those column
>>>>> names in the second row(which contains maximum 100 000 columns) ?
>>>>> 
>>>>> I am using the results during the write time & not before presentation
>>>>> to the user, so latency wont be much concern while writing.
>>>>> 
>>>>> Is it the proper way to procure intersection results of two rows ?
>>>>> 
>>>>> Would love to hear your comments..
>>>>> 
>>>>> 
>>>>> ---------
>>>>> 
>>>>> Regards,
>>>>> Asil
>>>>> 
>>>>> 
>>>> 
>>>> --
>>>> View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Finding-the-intersection-results-of-column-sets-of-two-rows-tp5997248p5997743.html
>>>> Sent from the cassandra-user@incubator.apache.org mailing list archive at
Nabble.com.
>>>> 
>>> 
>>> You can use multi-get when fetching lists of already know keys
>>> optimize your round rip time.
>>> 


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