Michael A Chase tech wrote on 12/13/2004, 9:24 AM:
> On 12/13/2004 06:09 AM, Hardy Merrill said:
>
> > I realize I'm splitting hairs here, and I'm no database expert, but I'm
> > curious about your answer to this - wouldn't this be even slightly more
> > efficient to write the WHERE clause conditions as most restricting
> > first? In other words,
> >
> > SELECT feature.id
> > FROM feature,
> > reporter
> > WHERE reporter.attributes_id = ? <=== most restrictive 1st
> > AND feature.reporter_id = reporter.id <=== next most
> > restrictive
> >
> > I was once told (or read?) that it is most efficient to put the most
> > restrictive conditions first in the WHERE - is that right? I've always
> > tended to put my joins towards the end of the WHERE when I have other
> > criteria that I'm looking for - just curious to know if I've been doing
> > it wrong.
>
> The general answer is that it all depends. A RDBMS builds its search
> plans based on a lot of factors; the order of the arguments may or may
> not be one of them.
>
For instance, a long time ago in sybase it mattered. Now the actual order
doesn't have that much influence.
> --
> Mac :})
> ** I usually forward private questions to the appropriate mail list. **
> Ask Smarter: http://www.catb.org/~esr/faqs/smart-questions.html
> Give a hobbit a fish and he eats fish for a day.
> Give a hobbit a ring and he eats fish for an age.
--
Your Friendly Neighborhood DBA,
Chuck
