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

"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> On Mon, Aug 17, 2020 at 8:31 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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