Date: Tue, 5 Oct 2021 16:15:43 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Stefan Keller <sfkeller@gmail.com>
Cc: Mark Rofail <markm.rofail@gmail.com>,
	Daniel Gustafsson <daniel@yesql.se>,
	vignesh C <vignesh21@gmail.com>,
	Alexander Korotkov <aekorotkov@gmail.com>,
	Andreas Karlsson <andreas@proxel.se>,
	David Steele <david@pgmasters.net>, Erik Rijkers <er@xs4all.nl>,
	=?utf-8?B?SGFucy1Kw7xyZ2VuIFNjaMO2bmln?= <hs@cybertec.at>,
	Joel Jacobson <joel@compiler.org>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Michael Paquier <michael@paquier.xyz>,
	Robert Haas <robertmhaas@gmail.com>,
	Stephen Frost <sfrost@snowman.net>, Tom Lane <tgl@sss.pgh.pa.us>,
	Zhihong Yu <zyu@yugabyte.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] GSoC 2017: Foreign Key Arrays
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Hi Stefan,

On 2021-Oct-03, Stefan Keller wrote:

> Just for my understanding - and perhaps as input for the documentation of this:
> Are Foreign Key Arrays a means to implement "Generic Foreign Keys" as
> in Oracle [1] and Django [2], and of "Polymorphic Associations" as
> they call this in Ruby on Rails?

No -- at least as far as I was able to understand the pages you linked to.

It's intended for array elements of one column to reference values in a
scalar column.  These are always specific columns, not "generic" or
"polymorphic" (which I understand to mean one of several possible
columns).

Thanks,

-- 
Álvaro Herrera           39°49'30"S 73°17'W  —  https://www.EnterpriseDB.com/