Re: Emitting JSON to file using COPY TO

Andrew Dunstan <andrew@dunslane.net>

From: Andrew Dunstan <andrew@dunslane.net>
To: Davin Shearer <davin@apache.org>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Joe Conway <mail@joeconway.com>
Date: 2023-12-05T20:55:53Z
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>

On 2023-12-05 Tu 14:50, Davin Shearer wrote:
> Hi Joe,
>
> In reviewing the 005 patch, I think that when used with FORCE ARRAY, 
> we should also _imply_ FORCE ROW DELIMITER.  I can't envision a use 
> case where someone would want to use FORCE ARRAY without also using 
> FORCE ROW DELIMITER.  I can, however, envision a use case where 
> someone would want FORCE ROW DELIMITER without FORCE ARRAY, like maybe 
> including into a larger array.  I definitely appreciate these options 
> and the flexibility that they afford from a user perspective.
>
> In the test output, will you also show the different variations with 
> FORCE ARRAY and FORCE ROW DELIMITER => {(false, false), (true, false), 
> (false, true), (true, true)}?  Technically you've already shown me the 
> (false, false) case as those are the defaults.
>
>

I don't understand the point of FORCE_ROW_DELIMITER at all. There is 
only one legal delimiter of array items in JSON, and that's a comma. 
There's no alternative and it's not optional. So in the array case you 
MUST have commas and in any other case (e.g. LINES) I can't see why you 
would have them.


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com