Re: [Q] what difference between PK and unique index + not NULL??

  • From: Connor McDonald <hamcdc@xxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 19 Jan 2005 03:12:27 +0000 (GMT)

I think JL refers to unique constraints versus PK constraints, as opposed to 
unique index.  I
haven't done any tests but I remember reading somewhere that some materialised 
view rewrite
functionality depended on unique/pk *constraint* definition as opposed to 
unique *index*


 --- Jared Still <jkstill@xxxxxxxxx> wrote: 
> On Tue, 18 Jan 2005 11:27:49 -0800, Jacques Kilchoer
> <Jacques.Kilchoer@xxxxxxxxx> wrote:
> > The Oracle optimizer might view a PK constraint differently than a
> > unique constraint on not null columns, one of the performance experts on
> > the list could probably say a word or two about that.
> Jonathan does not mention the optimizer, though it appears from
> the article that the CBO may consider a UK with NOT NULL as
> identical to a PK.
> -- 
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist
> --
> //

Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
ISBN: 1590592174

email: connor_mcdonald@xxxxxxxxx

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