Re: Emitting JSON to file using COPY TO

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