Re: More new SQL/JSON item methods

At Thu, 1 Feb 2024 09:19:40 +0530, Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote in
> > As Tom suggested, given that similar situations have already been
> > disregarded elsewhere, worrying about excessively long input strings
> > in this specific instance won't notably improve safety in total.
> >
> > > Also, for non-string input, we need to convert numeric to string just for
> > > the error message, which seems overkill.
> >
> > As I suggested and you seem to agree, using literally "Nan or
> > Infinity" would be sufficient.
> >
>
> I am more concerned about .bigint() and .integer(). We can have errors when
> the numeric input is out of range, but not NaN or Infinity. At those
> places, we need to convert numeric to string to put that value into the
> error.
> Do you mean we should still put "Nan or Infinity" there?
>
> This is the case:
> select jsonb_path_query('12345678901', '$.integer()');
> ERROR: numeric argument of jsonpath item method .integer() is out of
> range for type integer

Ah.. Understood. "NaN or Infinity" cannot be used in those
cases. Additionally, for jpiBoolean and jpiBigint, we lack the text
representation of the value.

By a quick grepping, I found that the following functions call
numeric_out to convert the jbvNumeric values back into text
representation.

JsonbValueAstext, populate_scalar, iterate_jsonb_values,
executeItemOptUnrwapTarget, jsonb_put_escaped_value

The function iterate_jsonb_values(), in particular, iterates over a
values array, calling numeric_out on each iteration.

The following functions re-converts the converted numeric into another type.

jsonb_int[248]() converts the numeric value into int2 using numeric_int[248]().
jsonb_float[48]() converts it into float4 using numeric_float[48]().

Given these facts, it seems more efficient for jbvNumber to retain the
original scalar value, converting it only when necessary. If needed,
we could also add a numeric struct member as a cache for better
performance. I'm not sure we refer the values more than once, though.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center