Re: Rename or Re-Create Constraints?

On Sat, Apr 9, 2011 at 12:58 PM, Tom Lane  wrote:
> ALTER INDEX accounts_pkey RENAME TO whatever
>
> On very old versions of PG you may have to spell that "ALTER TABLE"
> instead of "ALTER INDEX", but it's the same thing either way.

Thank you so much for clearing that up for me Tom! I just couldn't
find anything documented or do I understand SQL enough to work through
that w/o an example.

I read the PostgreSQL documentation all morning and just couldn't find
it. Also to make sure I did this correct, if I had an existing table
w/o a PRIMARY KEY index / constraint, is the following correct?

CREATE UNIQUE INDEX users_pkey ON public.users (id);
CREATE INDEX

I'm guessing that's how I generate a index / constraint on an existing
table when it was generated during the table creation SQL command,
right?

Is there a difference between an INDEX and a CONSTRAINT?