From: | "Josh Berkus" <josh(at)agliodbs(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Bell <acbell(at)iastate(dot)edu> |
Cc: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: Primary Keys |
Date: | 2001-11-27 16:46:01 |
Message-ID: | web-514320@davinci.ethosmedia.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-novice |
Andrew,
> > Can someone tell me what advantage there is to creating a table
> with a
> > primary key rather than simply adding a unique index to the table
> at a
> > later time.
If you are a serious DBA, one of the important rules to follow is "Never
create any table without a Primary Key." One can achieve the same
result by adding a UNIQUE index on a NOT NULL column later, but the
danger is that you'll forget and go into production with an un-keyed
table. Believe me, I've done it, and didn't realize what was wrong
until I got a "Could not identify unique tuple" error.
For an extensive discussion of why primary keys are important, see
"Practical Issues in Database Management" (F. Pascal).
-Josh Berkus
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