Re: SQL Performance Tuning--do the right thing

Thanks for the info...and we are on 8i.

Sybrand Bakker wrote:
>
>
> The best approach depends on version, which you don't mention. The CBO in
> Oracle 8i has the in-list iterator, which breaks up the IN and processes
 all
> elements seperately. IN ... in Oracle 7 would result in a full table
 scan,
> OR would use the index, provided the selectivity of the index is
 sufficient.
> As companion to the Harrison book you may consider obtaining the book of
> Richard Niemic on performance tuning published by Osborne/Oracle Press.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
>
>
> "mr_oatmeal" <mr_oatmeal_at_hotmail.com> wrote in message
> news:t1lmqto65icb14_at_corp.supernews.com...
> > Hi I'm taking over some code that was writen by a contractor...and I
 need
> > to go through and improve the embedded sql stmnts. I've been doing so
 to
> > the best of my knowledge...then i run accross something like this. For
> > performance, would it be more efficient to use the in clause rather
 than
> > the OR. (both return the same data)
> >
> > Are there any other hints/tips that you can give me for improving
> > performance, things that kill the use of the index, anything would
 help--
> > we don't have a dba. I've been reading a book called Oracle SQL High
> > Performance Tuning. If you know of any others please send 'em.
> >
> > SELECT author_code, first_name
> > FROM table
> > WHERE status = 'author'
> > OR status = 'columnist'
> > OR status = 'deputy bureau chief'
> > OR status = 'bureau chief'
> >
> > ---------
> >
> > SELECT author_code, first_name
> > FROM table
> > WHERE status IN ('author','columnist','deputy bureau chief','bureau
> > chief')
> >
> >
> > mr_oatmeal
> >
> > --
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> > http://www.help.com/
>
>

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