Xref: alice comp.databases.oracle.server:52213 Message-ID: <375AD193.5B49C079@deere.com> Date: Sun, 06 Jun 1999 14:52:52 -0500 From: John Higgins X-Mailer: Mozilla 4.6 [en]C-NECCK (Win95; I) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.databases.oracle.server Subject: Re: Unique Constraint vs Unique Index References: <7jbrrg$5fo$1@imsp009a.netvigator.com> <01beb003$0b1a0e40$8909eec3@default> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: 6 Jun 1999 14:52:55 -0600, 164.121.208.102 Lines: 29 Path: alice!news-feed.fnsi.net!netnews.com!news.maxwell.syr.edu!newspeer.monmouth.com!news-xfer.epix.net!uunet!ffx.uu.net!in5.uu.net!news1.dpn.deere.com!164.121.208.102 I'm not sure where you were looking, but both the 7.3.3 and the 8.0.5 documentation cdroms include the create unique index syntax. Oracle recommends the constraint approach. They say that the uniqueness requirement is properly considered an attribute of the table. In today's versions, Oracle then uses an index to enforce the unique constraint. Fututre technology (I have no idea what) may develope a better way than an index to enforce uniqueness. GDN wrote: > When you take a look at the SQL-reference for Oracle 7, you see that the > "create unique index... " statements doesn't exist any more. You can > consider it as a hidden feature. > So, you cannot be sure that it will work in future version of Oracle. > > GDN > > Lyx wrote in article > <7jbrrg$5fo$1@imsp009a.netvigator.com>... > > I am a newbie and determining on which methods (unique constraint or > > unique index) would be better for a Data WH design. > > Should there be any difference between a unique constraint or purely > > unique index applied except for enabling/disabling constraint? > > Also, what will be the internal engine done if a constraint is applied? > > > > Thanks! > >