Re: remaining sql/json patches

From: jian he <jian(dot)universality(at)gmail(dot)com>
To: Erik Rijkers <er(at)xs4all(dot)nl>
Cc: Amit Langote <amitlangote09(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: remaining sql/json patches
Date: 2023-09-19 10:37:45
Message-ID: CACJufxFgiu2320o9C2Pu+tNt3zKqJZ7NVVU5dWCjV=Ftp6rz_w@mail.gmail.com
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On Mon, Sep 18, 2023 at 7:51 PM Erik Rijkers <er(at)xs4all(dot)nl> wrote:
>
> and FYI: None of these crashes occur when I leave off the 'WITH WRAPPER'
> clause.
>
> >
> > Erik
> >

if specify with wrapper, then default behavior is keep quotes, so
jexpr->omit_quotes will be false, which make val_string NULL.
in ExecEvalJsonExprCoercion: InputFunctionCallSafe, val_string is
NULL, flinfo->fn_strict is true, it will return: *op->resvalue =
(Datum) 0. but at the same time *op->resnull is still false!

if not specify with wrapper, then JsonPathQuery will return NULL.
(because after apply the path_expression, cannot multiple SQL/JSON
items)

select json_query(jsonb'{"a":[{"a":3},{"a":[4,5]}]}','$.a[*].a?(@<=3)'
returning int4range);
also make server crash, because default is KEEP QUOTES, so in
ExecEvalJsonExprCoercion jexpr->omit_quotes will be false.
val_string will be NULL again as mentioned above.

another funny case:
create domain domain_int4range int4range;
select json_query(jsonb'{"a":[{"a":[2,3]},{"a":[4,5]}]}','$.a[*].a?(@<=3)'
returning domain_int4range with wrapper);

should I expect it to return [2,4) ?
-------------------
https://www.postgresql.org/docs/current/extend-type-system.html#EXTEND-TYPES-POLYMORPHIC
>> When the return value of a function is declared as a polymorphic type, there must be at least one argument position that is also
>> polymorphic, and the actual data type(s) supplied for the polymorphic arguments determine the actual result type for that call.

select json_query(jsonb'{"a":[{"a":[2,3]},{"a":[4,5]}]}','$.a[*].a?(@<=3)'
returning anyrange);
should fail. Now it returns NULL. Maybe we can validate it in
transformJsonFuncExpr?
-------------------

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