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From David Boxenhorn <da...@lookin2.com>
Subject Re: N to N relationships
Date Thu, 09 Dec 2010 13:38:07 GMT
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, S├ębastien 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,
>
> S├ębastien Druon
>

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