Re: New "raw" COPY format

From: "Daniel Verite" <daniel(at)manitou-mail(dot)org>
To: "Joel Jacobson" <joel(at)compiler(dot)org>
Cc: Jacob Champion <jacob(dot)champion(at)enterprisedb(dot)com>, Tatsuo Ishii <ishii(at)postgresql(dot)org>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: New "raw" COPY format
Date: 2024-10-16 16:34:13
Message-ID: d3313604-fbdd-483f-9c29-aceaf491f949@manitou-mail.org
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Joel Jacobson wrote:

> However, I thinking rejecting such column data seems like the
> better alternative, to ensure data exported with COPY TO
> can always be imported back using COPY FROM,
> for the same format.

On the other hand, that might prevent cases where we
want to export, for instance, a valid json array:

copy (select json_agg(col) from table ) to 'file' RAW

This is a variant of the discussion in [1] where the OP does:

copy (select json_agg(row_to_json(t)) from <query> t) TO 'file'

and he complains that both text and csv "break the JSON".
That discussion morphed into a proposed patch adding JSON
format to COPY, but RAW would work directly as the OP
expected.

That is, unless <query> happens to include JSON fields with LF/CRLF
in them, and the RAW format says this is an error condition.
In that case it's quite annoying to make it an error, rather than
simply let it pass.

[1]
https://postgr.es/m/CALvfUkBxTYy5uWPFVwpk_7ii2zgT07t3d-yR_cy4sfrrLU=kcg@mail.gmail.com

Best regards,
--
Daniel Vérité
https://postgresql.verite.pro/
Twitter: @DanielVerite

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