Thread: Unique Index vs. Unique Constraint
Does a Unique Constraint build a unique index? What is the difference? Thanks, Thomas LeBlanc _________________________________________________________________ Get a FREE computer virus scan online from McAfee. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
On Fri, 10 Oct 2003 13:59:38 -0500, "Thomas LeBlanc" <thomasatiem@hotmail.com> wrote: >Does a Unique Constraint build a unique index? Yes. >What is the difference? A constraint is an abstract concept, an index is an implementation detail. Servus Manfred
On Fri, 10 Oct 2003, Thomas LeBlanc wrote: > Does a Unique Constraint build a unique index? > > What is the difference? None that I know of.
Then what is the difference in these two statements? alter table Table1 add constraint Table1_UC1 unique (Field1, Field2) and create unique index Table1_Field1Field2 on Table1 (Field1, Field2) Thanks, Thomas LeBlanc >From: Dennis Gearon <gearond@fireserve.net> >To: Thomas LeBlanc <thomasatiem@hotmail.com> >Subject: Re: [GENERAL] Unique Index vs. Unique Constraint >Date: Fri, 10 Oct 2003 15:16:12 -0700 > >Uniquely so! > >Thomas LeBlanc wrote: > >>Does a Unique Constraint build a unique index? >> >>What is the difference? >> >>Thanks, >>Thomas LeBlanc >> >>_________________________________________________________________ >>Get a FREE computer virus scan online from McAfee. >>http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 >> >> >>---------------------------(end of broadcast)--------------------------- >>TIP 6: Have you searched our list archives? >> >> http://archives.postgresql.org >> > _________________________________________________________________ Help protect your PC. Get a FREE computer virus scan online from McAfee. http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
scott.marlowe wrote: > On Fri, 10 Oct 2003, Thomas LeBlanc wrote: > >> Does a Unique Constraint build a unique index? >> >> What is the difference? > > None that I know of. A different implementation of UNIQUE constraint might allow deferrability, what our index solution does not ... yet. Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #