From: Harald Fuchs <hari.fuchs@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: Composite primary keys
Date: Wed, 24 Jun 2009 10:37:37 +0200
Message-ID: <puiqim10z2.fsf@srv.protecting.net> (raw)
References: <pu1vpb2d9f.fsf@srv.protecting.net>
<20090623184412.GG27474@eddie>
<24680.1245784517@sss.pgh.pa.us>
In article <24680.1245784517@sss.pgh.pa.us>,
Tom Lane <tgl@sss.pgh.pa.us> writes:
> Joshua Tolley <eggyknap@gmail.com> writes:
>> Primary keys are NOT NULL and UNIQUE. You can't have null values in a primary
>> key.
> On reflection I think the OP's beef is that we complain about this:
> regression=# create table t (f1 int null not null);
> ERROR: conflicting NULL/NOT NULL declarations for column "f1" of table "t"
> but not this:
> regression=# create table t (f1 int null primary key);
> NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "t_pkey" for table "t"
> CREATE TABLE
> even though the implied NOT NULL is really a conflict.
Yes, that's exactly what I found strange.
> I think we could
> fix that case if we cared to. However, since the NULL clause is
> forgotten about after parsing, there isn't anything we could do to raise
> a complaint about doing it in two steps:
> regression=# create table t (f1 int null);
> CREATE TABLE
> regression=# alter table t add primary key(f1);
> NOTICE: ALTER TABLE / ADD PRIMARY KEY will create implicit index "t_pkey" for table "t"
> ALTER TABLE
> (barring remembering the NULL clause in the catalogs, which seems
> entirely silly).
I thought nullability is the default anyway, so indeed no need to
remember it. My gripe was really the first case, where you contradict
yourself in a single DDL statement.
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To: pgsql-sql@postgresql.org
Cc: hari.fuchs@gmail.com
Subject: Re: Composite primary keys
In-Reply-To: <puiqim10z2.fsf@srv.protecting.net>
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