Thanks a lot for the support!
On Thu, 2010-12-09 at 19:50 -0600, Nick Bailey wrote:
> I would also recommend two column families. Storing the key as NxN
> would require you to hit multiple machines to query for an entire row
> or column with RandomPartitioner. Even with OPP you would need to pick
> row or columns to order by and the other would require hitting
> multiple machines. Two column families avoids this and avoids any
> problems with choosing OPP.
>
> On Thu, Dec 9, 2010 at 2:26 PM, Aaron Morton <aa...@thelastpickle.com>
> wrote:
> Am assuming you have one matrix and you know the dimensions.
> Also as you say the most important queries are to get an
> entire column or an entire row.
>
>
> I would consider using a standard CF for the Columns and one
> for the Rows. The key for each would be the col / row number,
> each cassandra column name would be the id of the other
> dimension and the value whatever you want.
>
>
> - when storing the data update both the Column and Row CF
> - reading a whole row/col would be simply reading from the
> appropriate CF.
> - reading an intersection is a get_slice to either col or row
> CF using the column_names field to identify the other
> dimension.
>
>
> You would not need secondary indexes to serve these queries.
>
>
> Hope that helps.
> Aaron
>
>
>
> On 10 Dec, 2010,at 07:02 AM, Sébastien Druon
> <sdr...@spotuse.com> wrote:
>
>
> > I mean if I have secondary indexes. Apparently they are
> > calculated in the background...
> >
> > On 9 December 2010 18:33, David Boxenhorn
> > <da...@lookin2.com> wrote:
> > What do you mean by indexing?
> >
> >
> >
> > On Thu, Dec 9, 2010 at 7:30 PM, Sébastien Druon
> > <sdr...@spotuse.com> wrote:
> > 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
> > <da...@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 <sdr...@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
> >
> >
> >
> >
> >
> >
> >
> >
>
