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

From: Connor McDonald <hamcdc_at_yahoo.co.uk>
Date: Wed, 19 Jan 2005 03:12:27 +0000 (GMT)
Message-ID: <20050119031227.32711.qmail@web86905.mail.ukl.yahoo.com>

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_at_gmail.com> wrote:
  > On Tue, 18 Jan 2005 11:27:49 -0800, Jacques Kilchoer
  > <Jacques.Kilchoer_at_quest.com> 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
  > --
  > http://www.freelists.org/webpage/oracle-l
  >
  

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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_at_yahoo.com

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Received on Tue Jan 18 2005 - 22:15:05 CST