Re: Tackling JsonPath support

2016-11-29 2:50 GMT+01:00 Christian Convey <christian(dot)convey(at)gmail(dot)com>:

> On Mon, Nov 28, 2016 at 11:23 AM, Nico Williams <nico(at)cryptonector(dot)com>
> wrote:
> ...
>
>> JSON Path is not expressive enough (last I looked) and can be mapped
>> onto jq if need be anyways.
>>
>
> ​Hi Nico,
>
> Could you please clarify what you mean by "not expressive enough"?
>
> I ask because I've been struggling to identify clear requirements for the
> json-path functionality I'm trying to provide. It sounds like perhaps you
> have something concrete in mind.
>
> Since I myself have no need currently for this functionality, I'm left
> guessing about hypothetical users of it.​ My current mental model is:
>
> (a) Backend web developers. AFAICT, their community has mostly settled on
> the syntax/semantics proposed by Stefan Groessner. It would probably be
> unkind for PG's implementation to deviate from that without a good reason.
>
> (b) PG hackers who will eventually implement the ISO SQL standard
> operators. In the standards-committee meeting notes I've seen, it seemed
> to me that they were planning to define some operators in terms of
> json-path expression. So it would probably be good if whatever json-path
> function I implement turns out to comply with that standard, so that the
> PG-hackers can use it as a building block for their work.
>
> (c) Pavel. (I'm still somewhat unclear on what has him interested in
> this, and what his specific constraints are.)
>

My target is simple - 1. to have good ANSI/SQL support, 2. to have good
JSON to relation mapping function - ANSI/SQL JSONTABLE does it.

We now support XPath function - JSONPath is similar to XPath - it is better
for user, because have to learn only one language.

Regards

Pavel

>
> - Christian
>
>