Xref: alice comp.databases.oracle.server:52192 Path: alice!news-feed.fnsi.net!news.idt.net!dispose.news.demon.net!demon!news.demon.co.uk!demon!jlcomp.demon.co.uk!not-for-mail From: "Jonathan Lewis" Newsgroups: comp.databases.oracle.server Subject: Re: Unique Constraint vs Unique Index Date: Sun, 6 Jun 1999 11:52:46 +0100 Message-ID: <928666602.14210.0.nnrp-13.9e984b29@news.demon.co.uk> References: <7jbrrg$5fo$1@imsp009a.netvigator.com> <01beb003$0b1a0e40$8909eec3@default> X-Trace: news.demon.co.uk 928666602 nnrp-13:14210 NO-IDENT jlcomp.demon.co.uk:158.152.75.41 X-Complaints-To: abuse@demon.net X-Newsreader: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Lines: 19 It's worth remembering that in Oracle 8 (possibly 8.1 only) a unique or pk constrain can be represented by a non-unique index (a) to save space, and (b) to allow for deferring the constraint until commit time. -- Jonathan Lewis Yet another Oracle-related web site: www.jlcomp.demon.co.uk GDN wrote in message <01beb003$0b1a0e40$8909eec3@default>... >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.