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help / color / mirror / Atom feedFrom: Robert Haas <[email protected]>
To: David G. Johnston <[email protected]>
Cc: Haibo Yan <[email protected]>
Cc: jian he <[email protected]>
Cc: Corey Huinker <[email protected]>
Cc: Zsolt Parragi <[email protected]>
Cc: Vik Fearing <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: implement CAST(expr AS type FORMAT 'template')
Date: Thu, 2 Jul 2026 17:16:52 -0400
Message-ID: <CA+TgmobibgO2a3UDr7DrbKVnDG9ZViYTn6+nKR3Kq88Aii7-fw@mail.gmail.com> (raw)
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On Thu, Jul 2, 2026 at 4:51 PM David G. Johnston
<[email protected]> wrote:
>> and the existence of a
>> format cast doesn't mean there has to be a regular cast.
>
> Disagree
OK, but on what basis?
If I want 'whatever'::thistype::thattype to fail and CAST(thistype AS
thattype FORMAT 'bumble') to succeed, then I need there to be a format
cast but not a regular cast. Apparently, you'd like to arbitrarily
disallow that case, but I can't see any logical reason for such a
prohibition. Essentially we'd be forcing the user to create a regular
cast that they don't want in order to be able to create a format cast
that they do want. If there were some reason why we had to couple the
two things together that way, that would be one thing, but as far as I
can see, there isn't.
--
Robert Haas
EDB: http://www.enterprisedb.com
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Subject: Re: implement CAST(expr AS type FORMAT 'template')
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