Horton

Re: Emitting JSON to file using COPY TO

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

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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>
Date: 2023-12-02T15:11:20Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add option force_array for COPY JSON FORMAT

  2. json format for COPY TO

  3. introduce CopyFormat, refactor CopyFormatOptions

  4. Doc: add IDs to copy.sgml's <varlistentry> and <refsect1>

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