Re: Transform for pl/perl

ilmari@ilmari.org (Dagfinn Ilmari Mannsåker) writes:

> Tom Lane <tgl@sss.pgh.pa.us> writes:
>
>> ilmari@ilmari.org (Dagfinn Ilmari =?utf-8?Q?Manns=C3=A5ker?=) writes:
>>> While playing around some more with the extension, I discoverered a few
>>> more issues:
>>> ...
>>> 4) SV_to_JsonbValue() throws an error for infinite NVs, but not NaNs
>>
>> The others sound like bugs, but that one's intentional, since type
>> numeric does have a concept of NaN.  If you're arguing that we should
>> disallow that value in the context of jsonb, maybe so, but it'd likely
>> take changes in quite a few more places than here.
>
> The numeric type that's used internally to represent numbers in jsonb
> might have the concept of NaN, but JSON itself does not:
>
>     Numeric values that cannot be represented in the grammar below (such
>     as Infinity and NaN) are not permitted.
>
>       - https://tools.ietf.org/html/rfc7159#section-6
[…]
>    =# create or replace function jsonbnan() returns jsonb immutable language plperlu transform for type jsonb as '0+"NaN"';
>    CREATE FUNCTION
[…]
>    =# select jsonbnan()::json;
>    ERROR:  invalid input syntax for type json
>    DETAIL:  Token "NaN" is invalid.
>    CONTEXT:  JSON data, line 1: NaN

Also, it doesn't parse back in as jsonb either:

    =# select jsonbnan()::text::json;
    ERROR:  invalid input syntax for type json
    DETAIL:  Token "NaN" is invalid.
    CONTEXT:  JSON data, line 1: NaN

And it's inconsistent with to_jsonb():

    =# select to_jsonb('nan'::numeric);
    ┌──────────┐
    │ to_jsonb │
    ├──────────┤
    │ "NaN"    │
    └──────────┘

It would be highly weird if PL transforms (jsonb_plpython does the same
thing) let you create spec-violating jsonb values that don't round-trip
via jsonb_out/in.

- ilmari
-- 
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