Feedback-ID: ia2694551:Fastmail
Date: Wed, 31 Jan 2024 14:26:28 +0100
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: jian he <jian.universality@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>,
	Joe Conway <mail@joeconway.com>, Daniel Verite <daniel@manitou-mail.org>,
	Andrew Dunstan <andrew@dunslane.net>, Davin Shearer <davin@apache.org>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Emitting JSON to file using COPY TO
Message-ID: <202401311326.zvfydnpkqnnd@alvherre.pgsql>
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On 2024-Jan-23, jian he wrote:

> > +           | FORMAT_LA copy_generic_opt_arg
> > +               {
> > +                   $$ = makeDefElem("format", $2, @1);
> > +               }
> >         ;
> >
> > I think it's not necessary. "format" option is already handled in
> > copy_generic_opt_elem.
> 
> test it, I found out this part is necessary.
> because a query with WITH like `copy (select 1)  to stdout with
> (format json, force_array false); ` will fail.

Right, because "FORMAT JSON" is turned into FORMAT_LA JSON by parser.c
(see base_yylex there).  I'm not really sure but I think it might be
better to make it "| FORMAT_LA JSON" instead of invoking the whole
copy_generic_opt_arg syntax.  Not because of performance, but just
because it's much clearer what's going on.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/