Re: SQL vs. Oracle

Sorry.... Even if your data is neatly sorted... continue ranting...

Daniel
Austin,TX

"Daniel" <delj_at_flash.net> wrote in message news:86qk9t$2d9_at_journal.concentric.net...
> I disagree. Even if your date is neatly sorted in the database, you still
> scan the entire table. Just experiment a little with cost on explain
plan.
> It is not effecient.
>
> Daniel
> Austin, TX
>
> "Terry Dykstra" <tdykstra_at_cfol.ab.ca> wrote in message
> news:vq4k4.95395$n3.1904625_at_news0.telusplanet.net...
> > If you have skewed data (e.g. 90% of your data has one value, the other
> 10%
> > has 5000 values), using an index definitely can be bad if you need to
> access
> > the single value that's in the 90% range.
> >
> > --
> > Terry Dykstra
> > Canadian Forest Oil Ltd.
> > Check out Sybase Developer's Network: http://www.sybase.com/sdn
> >
> > Daniel <delj_at_flash.net> wrote in message
> > news:86qio2$re_at_journal.concentric.net...
> > > Don't know 'bout you but most of my tables are very large. If it
isn't
> > > using an index, it is doing a full table scan and beating my hard
drives
> > to
> > > death. In addition to beating my hard drives, it takes much longer to
> do
> > a
> > > full table scan. Cost based optimization would try to use indexes,
not
> > > rules based. First rows is good if you want to use hints. See my
> > original
> > > example. The RDBMS should have used the index for an inner join. The
> > index
> > > was there. It is faster and more cost efficient to use the index, why
> > > should I have to tell the most powerful and expensive RDBMS on the
> planet,
> > > to use an index that is available for the field referenced in my where
> > > clause. The only time using an index is bad, is when the index is
> > corrupt.
> > > Can you think of an example to support your statement that sometimes
it
> is
> > > bad?
> > >
> > > Daniel
> > > Austin, TX
> > >
> > > > What makes using an index so good ?
> > > >
> > > > Sometimes using an index is good - sometimes its bad.
> > > >
> > > > If you want to use the index in almost all situations, make your
> > > > optimiser rule based or first rows based.
> > > >
> > > > HTH
> > > > --
> > > > ===========================================
> > > > Connor McDonald
> > > > "These views mine, no-one elses etc etc"
> > > > connor_mcdonald_at_yahoo.com
> > > >
> > > > "Some days you're the pigeon, and some days you're the statue."
> > >
> > >
> >
> >
>
>
Received on Thu Jan 27 2000 - 17:28:39 CST