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From: Joe Conway <mail@joeconway.com>
To: Andrew Dunstan <andrew@dunslane.net>
To: Davin Shearer <davin@apache.org>
To: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Emitting JSON to file using COPY TO
Date: Mon, 4 Dec 2023 08:37:23 -0500
Message-ID: <c30fc5da-0348-4e44-b699-804ccbdcfc36@joeconway.com> (raw)
In-Reply-To: <9c77b6fa-ee88-b2e6-0fa7-4fc81721da35@dunslane.net>
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	<b604b474-e2b2-4ba0-bc60-fd0cbc05cfc9@joeconway.com>
	<9c77b6fa-ee88-b2e6-0fa7-4fc81721da35@dunslane.net>

On 12/4/23 07:41, Andrew Dunstan wrote:
> 
> On 2023-12-03 Su 20:14, Joe Conway wrote:
>> (please don't top quote on the Postgres lists)
>>
>> On 12/3/23 17:38, Davin Shearer wrote:
>>> " being quoted as \\" breaks the JSON. It needs to be \".  This has 
>>> been my whole problem with COPY TO for JSON.
>>>
>>> Please validate that the output is in proper format with correct 
>>> quoting for special characters. I use `jq` on the command line to 
>>> validate and format the output.
>>
>> I just hooked existing "row-to-json machinery" up to the "COPY TO" 
>> statement. If the output is wrong (just for for this use case?), that 
>> would be a missing feature (or possibly a bug?).
>>
>> Davin -- how did you work around the issue with the way the built in 
>> functions output JSON?
>>
>> Andrew -- comments/thoughts?
> 
> I meant to mention this when I was making comments yesterday.
> 
> The patch should not be using CopyAttributeOutText - it will try to
> escape characters such as \, which produces the effect complained of
> here, or else we need to change its setup so we have a way to inhibit
> that escaping.


Interesting.

I am surprised this has never been raised as a problem with COPY TO before.

Should the JSON output, as produced by composite_to_json(), be sent 
as-is with no escaping at all? If yes, is JSON somehow unique in this 
regard?

-- 
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com






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