Re: Oracle Myths

Connor McDonald wrote:

> Pascal Byrne wrote:
> >
> > "Niall Litchfield" <n-litchfield_at_audit-commission.gov.uk> wrote in message news:<3ce21b71$0$8510$ed9e5944_at_reading.news.pipex.net>...
> > > PCTIncrease should be as small as possible but non-zero to minimize
> > > tablespace fragmentation.1% is a good value (from my OCP course notes though
> > > not necessarily given by the tutor!)
> >
> > I've seen this quoted in a recent paper by Michael R. Ault (author of
> > "Oracle8i Administration and Management"). The reason given was that
> > SMON will not coalesce free space if PCTINCREASE is zero. Is this
> > definitly a myth?
> >
> > -Pascal
>
> I like to think of it like this...
>
> a) Take a wooden house
> b) Smash it to pieces with a hammer (ie its now "fragmented")
> c) Get some nails
> d) Use the hammer to put the house back to together ("defragment")
>
> Voila! We can now proclaim that a hammer is an effective defragmentation
> device.
>
> pctincrease is the same. You set to 1 (which causes fragmentation more
> often than now), and then claim that setting it to 1 will solve the very
> problem that they've just caused.
>
> hth
> connor
> --
> ==============================
> Connor McDonald
>
> http://www.oracledba.co.uk
>
> "Some days you're the pigeon, some days you're the statue..."

The original point of setting pctincrease in the tablespace to 1 was not that it would ever be used. Just to force the clean-up. The reason to use 1, rather than 50, was that if a mistake did take place it wouldn't make as big a mess.

Daniel Morgan Received on Mon May 20 2002 - 10:39:41 CDT