Re: TRM and sorts

paul c wrote:
> I wonder if anybody here has spent much time thinking about the
> practicalities of the "trans-relational model"?
>
> I can see its value for joins that don't involve projections of
> relations that have a great many attributes, however it seems to assume
> that all "tables" are pre-sorted (which for some apps I think is a
> reasonable assumption) and since "ORDERing" often involves permutations
> of attributes, I think that any implementation that supports ordering on
> multiple attributes must either pre-sort every permutation of attributes
> or implement the equivalent of a run-time sort.
>
> Sometimes I wonder if this is one reason why it might be thought
> deficient. I'm curious as to what others here might condider practical
> deficiencies.

It's been a couple of years (at least) since I read anything concrete about the TRM, but my impression was that all the columns were always sorted - so run-time sorts on single columns are unnecessary, and when you have to sort data on multiple columns, you should be able to preserve the order of the lead column of the sort, which should simplify the sorting (if only because you only have to sort each subrange with the same lead column).

Am I wrong on that?

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2007.0826 -- http://dbi.perl.org/