Re: DISTINCT vs. GROUP BY

On Tue, Sep 20, 2005 at 06:45:07PM -0400, Bruce Momjian wrote:
> Jim C. Nasby wrote:
> > > What do these URL's have that the current TODO does not?
> > > 
> > > * Consider using hash buckets to do DISTINCT, rather than sorting
> > > 
> > >   This would be beneficial when there are few distinct values.  This is
> > >   already used by GROUP BY.
> > 
> > Maybe it's just me, but the recent run-through of the TODO list
> > indicated that there's a fair number of items that people look at and
> > don't really knowh what they mean. Providing the context (ie: email
> > thread) that spawned an idea seems extremely valuable in being able to
> > explain the idea behind a TODO item. They also usually contain valuable
> > tips about how a TODO could be implemented. In this example, having
> > quick reference to the discussion about hashagg and first()/last() would
> > probably prove useful.
> 
> True, but sometimes the thread winds all around and there isn't a
> definative explaination of how to go at something.  I woul rather digest
> the information to improve it, rather than require people to wade around
> in an email thread.  Is there some detail the TODO is missing?

Sure, and I think the TODO items usually are digested fine. But if you
want to know any of the details behind the items (like what the
motivation is, or how it could be done), you have to manually go and
search the archives trying to find something.

In this example, it would have been useful to see if there had been any
discussion about if you could use hashagg to do this or not. But
searching the archive turned up nothing, so I guess we'll never know. If
there was a link to a thread in the TODO, we could see exactly what was
discussed.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461