Re: Unique and Primary Key Constraints

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Rod Taylor <rbt(at)zort(dot)ca>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Unique and Primary Key Constraints
Date: 2002-07-13 14:29:28
Message-ID: 200207131429.g6DETSM21306@candle.pha.pa.us
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Rod Taylor wrote:
> > > I prefer ...add constraint. After a while (release or 2) removal of
> > > create unique index all together.
> >
> > Remove CREATE UNIQUE INDEX entirely? Why?
>
> I was looking to encourage users to use core SQL as I spend more time
> than I want converting between systems -- thanks in part to users who
> create non-portable structures.
>
> Temporarily forgot there are index types other than btree :)

Not so much non-btree, but non-unique indexes themselves. UNIQUE index
is funny because it is a constraint and an performance utility. I see
your point that a constraint is more ANSI standard, but because we can't
get rid of non-unique indexes, I am not sure if there is really a good
reason to move to UNIQUE constraints. Well, it does make the table
definition and index more compact (one statement) but we split them up
on pg_dump so we can load the table without the index, so it doesn't
seem to be a win.

--
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