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From: jian he <jian.universality@gmail.com>
Date: Wed, 1 Apr 2026 15:23:07 +0800
Message-ID: 
 <CACJufxGRSV3j6g7feEkfu7WuLx7ocMte8mvVEwNh7XBfnpJd-A@mail.gmail.com>
Subject: Re: CAST(... ON DEFAULT) - WIP build on top of Error-Safe User
 Functions
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Amul Sul <sulamul@gmail.com>, Peter Eisentraut <peter@eisentraut.org>,
	Kirill Reshke <reshkekirill@gmail.com>,
 Vik Fearing <vik@postgresfriends.org>,
	Isaac Morland <isaac.morland@gmail.com>, pgsql-hackers@lists.postgresql.org
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One more issue I found:
https://git.postgresql.org/cgit/postgresql.git/commit/?id=74c96699be3f53c058c8794c07952221b9625b4f
SELECT JSON_VALUE(jsonb '1234', '$' RETURNING char(2)  DEFAULT '011' ON ERROR);
ERROR:  value too long for type character(2)

Similarly, we can
SELECT CAST(text '1234' as char(2) DEFAULT '111111' ON conversion ERROR);
ERROR:  value too long for type character(2)

Composite types respect typmod, for example:
CREATE TYPE comp AS (a char(3), b int);
SELECT CAST('(14,42)' AS comp DEFAULT '(1234,2)' ON CONVERSION ERROR); -- error

The regression tests are too large; we can order them by the cast
source type's pg_type.type category,
so we won't miss any tests.

What do you think?