Subject: Re: New "raw" COPY format

From: "Daniel Verite" <[email-masked]>
Date: Wed, 16 Oct 2024 18:34:13 +0200

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=[email-masked]

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