From: Richard Huxton <dev@archonet.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Jan Wieck <JanWieck@Yahoo.com>
Cc: Markus Bertheau <twanger@bluetwanger.de>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: olly@lfix.co.uk, pgsql-sql@postgresql.org, Bruce Momjian <pgman@candle.pha.pa.us>
Subject: Re: multi column foreign key for implicitly unique columns
Date: Wed, 18 Aug 2004 17:02:42 +0100
Message-ID: <41237DA2.9090405@archonet.com> (raw)
In-Reply-To: <22808.1092842209@sss.pgh.pa.us>
References: <1092734724.2627.4.camel@dicaprio.akademie1.de>
<1092735576.28365.48.camel@linda>
<1092736197.2627.12.camel@dicaprio.akademie1.de>
<200408171945.15663.josh@agliodbs.com>
<41235A90.1080300@Yahoo.com>
<1092836961.2630.3.camel@dicaprio.akademie1.de>
<41236277.5060903@Yahoo.com>
<22808.1092842209@sss.pgh.pa.us>
Tom Lane wrote:
> Jan Wieck <JanWieck@Yahoo.com> writes:
>
>>However, Bruce, this should be on the TODO list:
>> * Allow foreign key to reference a superset of the columns
>> covered by a unique constraint on the referenced table.
>
>
> See the followup discussion as to why this is a bad idea.
Maybe an alternative todo?
* Allow multiple unique constraints to share an index where one is a
superset of the others' columns.
That way you can mark it unique without having the overhead of multiple
indexes.
--
Richard Huxton
Archonet Ltd
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, tgl@sss.pgh.pa.us, JanWieck@Yahoo.com, twanger@bluetwanger.de, josh@agliodbs.com, pgman@candle.pha.pa.us
Subject: Re: multi column foreign key for implicitly unique columns
In-Reply-To: <41237DA2.9090405@archonet.com>
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