Re: COPY manual is ambiguous about column list

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pavlo Golub <pavlo(dot)golub(at)gmail(dot)com>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, "pgsql-docs(at)lists(dot)postgresql(dot)org" <pgsql-docs(at)lists(dot)postgresql(dot)org>
Subject: Re: COPY manual is ambiguous about column list
Date: 2019-12-20 15:01:28
Message-ID: 20191220150128.GD29807@momjian.us
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On Fri, Dec 20, 2019 at 07:29:33AM -0700, David G. Johnston wrote:
> This has the same "match by name" possibility when I read it...
>
> I don't see the benefit of repeating "If a column list is specified" a second
> time in the three sentence paragraph.  To a lesser extent the same goes for the
> second repetition of COPY FROM.
>
> I agree with the general goal of trying to get rid of the parenthetical; to
> that end:
> <command>COPY FROM</command> will match all listed columns in the table to
> *all* file columns by position.
>
> That sufficiently implies the "must have equal numbers" and, frankly, if
> someone gets that part wrong the immediate failure combined with re-reading the
> word "all" should provide sufficient clarity.
>
> So I'm still for Tom and mine combined proposal with cleaning up the middle
> sentence even more.
>
> The other point of note is the difference between:
>
> will receive their default value
> and
> will insert the default values
>
> The system is inserting default values but the columns are receiving them.  The
> sentence is relative to the table columns though so "receive" seems like the
> better fit.  Minor point overall though.

OK, this wording is obviously harder than I thought. Updated patch
attached.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +

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