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Re: Re: unique sequences

From: "DalTech - Continuing Technical Education" <CTE(at)Dal(dot)Ca>
To: <kparker(at)eudoramail(dot)com>
Cc: <pgsql-sql(at)hub(dot)org>
Subject: Re: Re: unique sequences
Date: 2000-06-27 11:12:16
Message-ID: 006601bfe028$8da6dd60$5911be86@cte.Dal.Ca (view raw, whole thread or download thread mbox)
Lists: pgsql-sql
I imagine it should if you create a unique index on the field.

Christopher Currie

----- Original Message -----
From: K Parker <kparker(at)eudoramail(dot)com>
To: <pgsql-sql(at)hub(dot)org>
Sent: Tuesday, June 27, 2000 1:52 AM
Subject: [SQL] Re: unique sequences

> > Rather, each time you wish to do an insert,
> > query the existing data to see what the
> > maximum value is existing in the database.
> > Add 1 to that and use this as your new value.
> > This is guaranteed to not have any holes in
> > the sequence.
> True, but alas it _doesn't_ guarantee uniqueness, since there's nothing to
prohibit 2 or more back ends getting the same max() at the
> same time...
> Thinking off the top of my head, I'm not sure you can apply FOR UPDATE to
an aggregate function, so there's probably no solution there, either.
> Join 18 million Eudora users by signing up for a free Eudora Web-Mail
account at

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