Re: LIMIT Optimization

On Fri, 25 Jan 2002, Bruce Momjian wrote:

> > if I'm not mistaken, it's called partial sorting, when you stop
> > sorting process after getting desired number of rows specified by LIMIT clause.
> > it's extremely friendly for web applications, because 90% of users
> > just read the first page of results. We already discussed this feature
> > sometime during 7.1 dev and even made very crude patch. In our tests we
> > got performance win of factor 5-6 ( getting first 100 row from 1mln ).
> > We hope sometime we'll return to this.
>
> But we already have cursor's assuming 10% return.  Is allowing that
> value to be changed using SET an acceptable solution?


Bruce, web applicationa are stateless, so forget about cursors.
I wrote about obvious optimization which is valid for very narrow case,
but which is widely spreaded.

>
>
Regards,    Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83