Re: Tackling JsonPath support

On Mon, Nov 28, 2016 at 9:40 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
wrote:
​...​

> > ​Hi Pavel,
> >
> > Can you clarify what you meant? I *think* you're saying:
> >
> > * It's not important for me to match the syntax/semantics of the
> json-path implementations found in MySQL / Oracle / DB2 / ​MS SQL Server,
> and
> >
>
> oh no. the syntax is important. But for start we can have a subset. For
> json table function .. json to relation mapping is important path
> expression. some other features like predicates
> are nice, but can be implemented later.
>
> Im sorry. My English is bad.
>
​Hi Pavel,

You're English is very good, actually. I think the confusion arises from
me speaking in vague terms. I apologize for that. Allow me to be more
specific about what I'm proposing to do.

I propose adding to "contrib" a function with the following characteristics:

* Its signature is "json_path( jsonb from_json, string
json_path_expression) --> jsonb".

* The function will hopefully be a useful building block for PG's
implementation of "official" JSON operators such as "JSON_TABLE". Once the
PG community agrees on what those operators' syntax/semantics should be.
​
* The function will hopefully be immediately useful to PG users who want
JSONPath -like operations on their "jsonb" objects.

- C