Re: SQL/JSON in PostgreSQL

From: Nikita Glukhov <n(dot)gluhov(at)postgrespro(dot)ru>
To: Piotr Stefaniak <email(at)piotr-stefaniak(dot)me>, "obartunov(at)gmail(dot)com" <obartunov(at)gmail(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>, Teodor Sigaev <teodor(at)postgrespro(dot)ru>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, andrew Dunstan <andrew(at)dunslane(dot)net>
Subject: Re: SQL/JSON in PostgreSQL
Date: 2017-11-03 11:29:33
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On 03.11.2017 00:32, Piotr Stefaniak wrote:

> On 2017-02-28 20:08, Oleg Bartunov wrote:
>> The standard describes SQL/JSON path language, which used by SQL/JSON query
>> operators to query JSON. It defines path language as string literal. We
>> implemented the path language as JSONPATH data type, since other
>> approaches are not friendly to planner and executor.
> I was a bit sad to discover that I can't
> I assume because of this part of the updated grammar:
> json_path_specification:
> Sconst { $$ = $1; }
> ;
> Would it make sense, fundamentally, to allow variables there? After
> Andrew Gierth's analysis of this grammar problem, I understand that it's
> not reasonable to expect JSON_TABLE() to support variable jsonpaths, but
> maybe it would be feasible for everything else? From Andrew's changes to
> the new grammar (see attached) it seems to me that at least that part is
> possible. Or should I forget about trying to implement the other part?
By standard only string literals can be used in JSON path specifications.
But of course it is possible to allow to use variable jsonpath
expressions in
SQL/JSON functions.

Attached patch implements this feature for JSON query functions,
not supported now because it needs some refactoring.

I have pushed this commit to the separate branch because it is not
finished yet:

Nikita Glukhov
Postgres Professional:
The Russian Postgres Company

Attachment Content-Type Size
0001-Allow-variable-jsonpath-specifications.patch text/x-patch 12.1 KB

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Michael Paquier 2017-11-03 11:53:42 Re: postgres_fdw: Add support for INSERT OVERRIDING clause
Previous Message Michael Paquier 2017-11-03 11:10:14 Re: [bug fix] postgres.exe crashes with access violation on Windows while starting up