Horton

Re: Inaccurate description of UNION/CASE/etc type selection

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Pg Docs <pgsql-docs@lists.postgresql.org>
Date: 2020-08-17T17:11:04Z
Lists: pgsql-docs

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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Mon, Aug 17, 2020 at 8:31 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> So this is just a verbatim statement of the algorithm, which is what
>> I was hoping to avoid :-(.  But maybe there's no simpler way.

> I got nothin'.

Yeah, me either.  So here's a proposed patch, fixing a couple other
things:

* Re-reading this, I thought the use of "preferred" in the existing
footnote about domains could be read as meaning that we treat the
base type as a preferred type; so I changed that.

* Something that's been true for a very long time, but never documented,
is that CASE puts its ELSE clause at the front for this purpose.
I figured that if we're trying to tell the full truth we better mention
that.

			regards, tom lane

Commits

  1. Doc: fix description of UNION/CASE/etc type unification.