Horton

Re: pgsql: Add more SQL/JSON constructor functions

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, pgsql-hackers@lists.postgresql.org
Date: 2024-05-29T16:44:35Z
Lists: pgsql-hackers 
Amit Langote <amitlangote09@gmail.com> writes:
> On Mon, May 27, 2024 at 7:10 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>> On 2024-May-27, Alvaro Herrera wrote:
>> I just noticed this behavior, which looks like a bug to me:
>> 
>> select json_serialize('{"a":1, "a":2}' returning varchar(5));
>> json_serialize
>> ────────────────
>> {"a":
>> 
>> I think this function should throw an error if the destination type
>> doesn't have room for the output json.  Otherwise, what good is the
>> serialization function?

> This behavior comes from using COERCE_EXPLICIT_CAST when creating the
> coercion expression to convert json_*() functions' argument to the
> RETURNING type.

Yeah, I too think this is a cast, and truncation is the spec-defined
behavior for casting to varchar with a specific length limit.  I see
little reason that this should work differently from

select json_serialize('{"a":1, "a":2}' returning text)::varchar(5);
 json_serialize 
----------------
 {"a":
(1 row)


			regards, tom lane

Commits

  1. SQL/JSON: Avoid initializing unnecessary ON ERROR / ON EMPTY steps

  2. SQL/JSON: Fix default ON ERROR behavior for JSON_TABLE

  3. SQL/JSON: Fix JSON_TABLE() column deparsing

  4. Update comment about ExprState.escontext

  5. SQL/JSON: Fix casting for integer EXISTS columns in JSON_TABLE

  6. SQL/JSON: Some fixes to JsonBehavior expression casting

  7. SQL/JSON: Remove useless code in ExecInitJsonExpr()

  8. SQL/JSON: Respect OMIT QUOTES when RETURNING domains over jsonb

  9. SQL/JSON: Improve error-handling of JsonBehavior expressions

  10. SQL/JSON: Fix error-handling of some JsonBehavior expressions

  11. SQL/JSON: Rethink c2d93c3802b

  12. SQL/JSON: Always coerce JsonExpr result at runtime

  13. SQL/JSON: Fix coercion of constructor outputs to types with typmod