Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation

On 29 avr, 23:01, "Brian Selzer" <b..._at_selzer-software.com> wrote:
> "Cimode" <cim..._at_hotmail.com> wrote in message
>
> news:1177873628.360842.277700_at_u30g2000hsc.googlegroups.com...
> [snip]
>
> > I can not say I disagree with what you are saying but I still think
> > you are missing the point of the example.
>
> > As a practionner who used intensively both procedural and set based
> > methods, on may manage to get response time to be faster using cursors
> > (that still need s to be established) but that does not mean that
> > performance as a whole is improved.
>
> > Self joins poor implementations is a known direct image systems
> > limitation. That is the issue I was trying to underline here.
> > Discussing tuning on a specific SQL DBMS implementation is not the
> > point of the thread nor the point of the NG. THe main point here is
> > to see if linear interpolation could be a way of handling
> > systematically missing numeric/datetime data...
>
> I think that self-joins would be problematic regardless of the
> implementation. They are necessary only when dependencies exist between
> tuples within the same relation. It's like using a single relation for
> graphs instead of one relation for verticies and a separate relation for
> edges. It can be done, but should it?
I do not understand where do you see a self join?

> On to your main point: Are you suggesting that the schema definition for a
> temporal relation include some form of "active" default definition, wherein
> a scalar expression would be stored in lieu of a value? Or maybe not
> stored, but evaluated whenever a missing value is accessed? Sounds like an
> interesting idea. I think the semantics would require some form of
> second-order logic, however.
I just think that handling missing data through NULLS is just the worst way of doing it. So I think interpolation may probably be closer to what Codd had in mind by formulating the prerequisite for a dbms to be able to have a *systematic way missing data*.(or at least numeric/datetime data)
> [snip]
Received on Mon Apr 30 2007 - 08:15:51 CEST