Re: Oracle Hints

Sybrand Bakker <postbus_at_sybrandb.demon.nl> wrote in message news:957982967.11610.0.pluto.d4ee154e_at_news.demon.nl...
>
> Gertjan <gr_at_compexbv.nl> schreef in berichtnieuws
> 8fc67m$29j$1_at_porthos.nl.uu.net...
> > In several messages I noticed that some of you are using optimizer
 hints?
 Is
> > using these hits advisable? Some of my colleques have advised me NOT to
 use
> > hints but to 'play around' with the were-clauses.
> >
> > Also, can anyone can give me some directions to sites or books that
 explain
> > hints???
> >
> > Thanx,
> > Gertjan
> >
> >
> The use of hints is a necessity as the perfect optimizer doesn't exist.
> If you are using the cost based optimizer playing around with where
 clauses
> is not going to make much difference. It will work in the rule based
> optimizer, which is still present in the software but has been obsoleted
> officially with Oracle 7.1, way back in 1993 or 1994.
>
> The hints are described in the Oracle docs, likely in the performance
 tuning
> guide. All docs are available at http://technet.oracle.com.
> They are definitely also in the tuning book of Rich Niemic, published by
> Osborne/Oracle Press.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>

Also, don't forget that for the cost based optimiser to work properley, you need to have up-to-date statistics.

Cheers,
John Blackburn Received on Thu May 11 2000 - 00:00:00 CDT