[Mondrian] Same dimension in different axis

[Brian Vandenberg]

  I agree with Pedro on this, even with using the same dimension on
rows/columns.  If I want information broken out by month & day of week, as
it stands I'd have to settle for one of:

* Break it out on one axis and live with it -- while I can't easily see
relationships between events that occur on mondays every month, there's not
much I can do about it otherwise.
* Create either a mirrored date dimension or a day of week dimension
** The mirrored date dimension could easily create confusion with users.
There's that saying "keep it simple, stupid".  More dimensions = more
complexity.
** The day of week dimension would suffice, but has some problems:
*** requires yet another dimension key on my fact table.  If my fact table
has many dimensions, more than one of which I'd like to use at different
levels of aggregation on different axes, this bloats the fact table
*** I would probably have to remove day of week from the date dimension,
which might be annoying under other circumstances where I want the date
dimension to have both month & day of week.  The date dimension can have
multiple drill-down paths, but that also creates more options for users --
and users don't like too many options
* Just break it out on one axis, then write custom code to iterate over the
query results in a different sequence than presented

  For whatever reason, it's easier for people to wrap their heads around few
columns with many rows, than many rows and fewer columns.  Additionally,
it'd be easier to see trends or patterns by applying the day of week on a
different axis from the month.

  While it's true a report or visualization would be _capable_ of presenting
the information in whatever way it sees fit, it'd be nice for the
[report/visualization] developer, and for those tech savvy users with just
enough knowledge to design simple queries.

  I see this as code re-use.  Why create 5 dimensions to represent the same
concept in different ways when one dimension would suffice if you have more
flexibility in its use.

-Brian

On Thu, Jul 16, 2009 at 4:06 AM, Pedro Alves <pedro at neraka.no-ip.org> wrote:

>
>
> Hey there.
>
>
> Is there a way to remove the restriction of not having the same dimension
> in more than one axis?
>
>
> I'm working on a dashboard generator that dynamically integrates with
> mondrian, but this is a very bad restriction if I want users to apply
> whatever filters they want. The following query is an example of the type
> of stuff I'd love to be able to do:
>
>
> select
>  Descendants([Products], [Products].[Version]) on rows,
>  Measures.[Downloads] on columns
> >From ...
> where
>  ([Dates].[Date].[2009-07-16],
>   [Products].[Firefox].[3.5],
>   [Download Types].[Complete])
>
>
> Instead, I need to do
>
>
> select
>  Descendants([Products].[Firefox].[3.5], [Products].[Version]) on rows,
>  Measures.[Downloads] on columns
> >From ...
> where
>  ([Dates].[Date].[2009-07-16],
>   [Download Types].[Complete])
>
>
> In terms of plain queries this is not complicated; But in a scenario where
> the users is free to choose whatever dimensions he wants to chart against
> whatever conditions he wants to filter, my algorithm to generate the query
> gets much more complicated than I'd like
>
>
> And I don't think there's a reason for this restriction; There were
> projects where I've defined in the mondrian schema the same dimension
> duplicated just to be able to do what I need. Another example is here:
> http://tinyurl.com/kk9b2b . Having to define a [Time2] dimension that's
> absolutely identical to [Time] to obtain a very standard crosstab
> information.
>
>
>
> Any tips appreciated
>
>
> -pedro
>
> _______________________________________________
> Mondrian mailing list
> Mondrian at pentaho.org
> http://lists.pentaho.org/mailman/listinfo/mondrian
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.pentaho.org/pipermail/mondrian/attachments/20090716/ac5c612e/attachment.html