From: Tom Lane <tgl@sss.pgh.pa.us>
To: Joe Conway <mail@joeconway.com>
cc: Nathan Bossart <nathandbossart@gmail.com>,
        Davin Shearer <davin@apache.org>,
        PostgreSQL-development <pgsql-hackers@postgreSQL.org>
Subject: Re: Emitting JSON to file using COPY TO
In-reply-to: <411395e0-697e-44ab-be98-dd2047f9a10e@joeconway.com>
References: <CALvfUkBxTYy5uWPFVwpk_7ii2zgT07t3d-yR_cy4sfrrLU=kcg@mail.gmail.com> <fc1e39f8-274f-4be6-8a70-9fb0d9fe84a2@aklaver.com> <CAFCRh-_LhP5Ln4-beVz=1pQ9VycU3hAxnJHXhPHZRmX0BSCVEQ@mail.gmail.com> <CAFCRh--Vhx0105S7SWAYHGcVMTSRtbcoArDUGSbYSWRUGunW_g@mail.gmail.com> <CAKFQuwZb3zaSqkOvGXRRLZEW61az+4xyHZ7tBPR91JfrcdCKvA@mail.gmail.com> <3853387.1701096982@sss.pgh.pa.us> <CAFCRh-_GdiUvjd5z5FfvTfhruOnYqBu163XU47zZE8RNATCJGQ@mail.gmail.com> <3a98decf-3fe3-4b49-9b68-fda01338872c@sedlakovi.org> <CALvfUkCq3pvkmniWEKZwkbA6hNNvkANF3OamMfhC170RgY+HJg@mail.gmail.com> <24e3ee88-ec1e-421b-89ae-8a47ee0d2df1@joeconway.com> <20231201230958.GA1786735@nathanxps13> <411395e0-697e-44ab-be98-dd2047f9a10e@joeconway.com>
Comments: In-reply-to Joe Conway <mail@joeconway.com>
	message dated "Sat, 02 Dec 2023 09:31:46 -0500"
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Date: Sat, 02 Dec 2023 10:11:20 -0500
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Joe Conway <mail@joeconway.com> writes:
>> I noticed that, with the PoC patch, "json" is the only format that must be
>> quoted.  Without quotes, I see a syntax error.  I'm assuming there's a
>> conflict with another json-related rule somewhere in gram.y, but I haven't
>> tracked down exactly which one is causing it.

While I've not looked too closely, I suspect this might be due to the
FORMAT_LA hack in base_yylex:

            /* Replace FORMAT by FORMAT_LA if it's followed by JSON */
            switch (next_token)
            {
                case JSON:
                    cur_token = FORMAT_LA;
                    break;
            }

So if you are writing a production that might need to match
FORMAT followed by JSON, you need to match FORMAT_LA too.

(I spent a little bit of time last week trying to get rid of
FORMAT_LA, thinking that it didn't look necessary.  Did not
succeed yet.)

			regards, tom lane