Re: Limits of SQL

Joachim Zobel schrob:

> Am Samstag, den 04.06.2005, 15:22 -0500 schrieb Bruno Wolff III:
>> On Sat, Jun 04, 2005 at 21:53:24 +0200,
>>   Joachim Zobel <jzobel@heute-morgen.de> wrote:
>> > So WITH will allow recursion so I can walk the graph, right? Does this
>> > mean I can recursively join until a terminating condition is reached?
>>
>> It can be used to compute transitive closures, which I think is what
>> you are really looking for.
>
> There aren't any plans to implement grouping by a user defined
> equivalence relation? This is the other thing I am missing. But OK, WITH

Isn't this already possible by representing the relation through its
canonical mapping (i.e. f(a)=f(b) <=> a relates to b)? You could then
use GROUP BY f(x) to group data into its equivalence classes.

regards,
Andreas