Date: Tue, 9 Jul 2019 15:34:48 +0900
From: Michael Paquier <michael@paquier.xyz>
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>, phil.bayer@gmail.com,
	pgsql-docs@lists.postgresql.org,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Postgres 11: Table Partitioning and Primary Keys
Message-ID: <20190709063448.GB23827@paquier.xyz>
References: <156236160709.1192.4498528196556144085@wrigleys.postgresql.org>
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 <20190709025856.GC1345@paquier.xyz>
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On Mon, Jul 08, 2019 at 08:12:18PM -0700, David G. Johnston wrote:
> Reads a bit backward.  How about:
>=20
> "As uniqueness can only be enforced within an individual partition when
> defining a primary key on a partitioned table all columns present in the
> partition key must also exist in the primary key."

Yes, I was not really inspired on this one.

Looking closely at the code in DefineIndex() (and as Rajkumar has
mentioned upthread for unique constraints) this can happen for primary
keys, unique constraints and exclusion constraints.  So we had better
mention all three of them.  I am not sure that we need to be explicit
about the uniqueness part though, let's say the following:
"When defining a primary key, a unique constraint or an exclusion
constraint on a partitioned table, all the columns present in the
constraint definition must be included in the partition key."
--
Michael

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