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*
hth
connor
--- 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.
>
> http://www.dbazine.com/jlewis21.shtml
>
> 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
> --
> //www.freelists.org/webpage/oracle-l
>
=====
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
ISBN: 1590592174
web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald@xxxxxxxxx
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