From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: psql display of foreign keys
In-reply-to: <20181204143834.ym6euxxxi5aeqdpn@alvherre.pgsql>
References: <20181204143834.ym6euxxxi5aeqdpn@alvherre.pgsql>
Comments: In-reply-to Alvaro Herrera <alvherre@2ndquadrant.com>
	message dated "Tue, 04 Dec 2018 11:38:34 -0300"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <23922.1543935600.1@sss.pgh.pa.us>
Date: Tue, 04 Dec 2018 10:00:00 -0500
Message-ID: <23923.1543935600@sss.pgh.pa.us>
Precedence: bulk

Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> This is not very useful.  I propose that we change it so that it only
> displays the one on the partitioned table on which the constraint was
> defined:

OK goal, but ...

> Patch attached.

... this patch breaks the expectation set at the top of describe.c:

 * Support for the various \d ("describe") commands.  Note that the current
 * expectation is that all functions in this file will succeed when working
 * with servers of versions 7.4 and up.  It's okay to omit irrelevant
 * information for an old server, but not to fail outright.

Do you really need WITH RECURSIVE for this?  If so, I'd suggest
applying it only when relkind == RELKIND_PARTITIONED_TABLE, so
that the case doesn't happen in servers too old to have WITH.
That's probably a win performance-wise anyway, as I have no doubt
that the performance of this query is awful compared to what it
replaces, so we don't really want to use it if we don't have to.

			regards, tom lane