Re: Which of these selects is faster?

In article <37158DF2.267F9493_at_vnl.nl>,
  Frank van Bortel <f.van.bortel_at_vnl.nl> wrote:
> silveys_at_my-dejanews.com wrote:
>
> > john0725_at_aol.com (John0725) wrote:
> > > If the where clause has ANDs then it is evaluated from the end of the
query
> > > towards the beginning, but if it has ORs it is evaluated starting closest
to
> > > the FROM clause and working its way downward.
> >
> > Thanks, it's helpful to know that things are sufficiently complex
> > that it seems oracle did not intend for users to predict the order
> > of evaluation. (That sucks of course, and I'd like to see them fix
> > it so that you could at least have the option to force a certain
> > order.)
> >
> > How did you come by this information? Trial and error? Oracle tech
> > support? Actual documentation? Source code?
>
> It quite logical, and documented.
> For the OR's, there's no point in evaluating, after a TRUE condition
> is found (TRUE or FALSE still is TRUE)- so this way of evaluating will
> actually speed up things.
> As for the ANDs, I think it's been there since V4, and I _know_
> it's still there because of V6 backward compatibility.
>
> I would need to check, but my best guess is the concepts manual is
> the place to find the documentation.
>
> --
> Met vriendelijke groet,
> kind regards,
>
> Frank van Bortel
> Technical consultant Oracle
> V&L Informatica BV
> -----------------------------------------------
> Work Home
> Postbus 545 Hunzestraat 4
> 7500 AM Enschede 7555 WB Hengelo
> (31)53.434.1500 (31)74.242.5046
>
>

-----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own Received on Thu Apr 15 1999 - 11:53:58 CDT