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From Sébastien Druon <sdr...@spotuse.com>
Subject Re: N to N relationships
Date Thu, 09 Dec 2010 17:30:28 GMT
Thanks a lot for the answer

What about the indexing when adding a new element? Is it incremental?

Thanks again

On 9 December 2010 14:38, David Boxenhorn <david@lookin2.com> wrote:

> How about a regular CF where keys are N@N ?
>
> Then, getting a matrix row would be the same cost as getting a matrix
> column (N gets), and it would be very easy to add element N+1.
>
>
> On Thu, Dec 9, 2010 at 1:48 PM, Sébastien Druon <sdruon@spotuse.com>wrote:
>
>> Hello,
>>
>> For a specific case, we are thinking about representing a N to N
>> relationship with a NxN Matrix in Cassandra.
>> The relations will be only between a subset of elements, so the Matrix
>> will mostly contain empty elements.
>>
>> We have a set of questions concerning this:
>> - what is the best way to represent this matrix? what would have the best
>> performance in reading? in writing?
>>   . a super column family with n column families, with n columns each
>>   . a column family with n columns and n lines
>>
>> In the second case, we would need to extract 2 kinds of information:
>> - all the relations for a line: this should be no specific problem;
>> - all the relations for a column: in that case we would need an index for
>> the columns, right? and then get all the lines where the value of the column
>> in question is not null... is it the correct way to do?
>> When using indexes, say we want to add another element N+1. What impact in
>> terms of time would it have on the indexation job?
>>
>> Thanks a lot for the answers,
>>
>> Best regards,
>>
>> Sébastien Druon
>>
>
>

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