Feedback-ID: ia2694551:Fastmail
Date: Sat, 7 Oct 2023 15:54:33 +0200
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Andres Freund <andres@anarazel.de>
Cc: Amit Langote <amitlangote09@gmail.com>,
	Andrew Dunstan <andrew@dunslane.net>, jian he <jian.universality@gmail.com>,
	Erik Rijkers <er@xs4all.nl>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: remaining sql/json patches
Message-ID: <202310071354.yljfgk2jgvvr@alvherre.pgsql>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20231006214856.yie5dedhzrcb3qxx@alap3.anarazel.de>
Archived-At: 
 <https://www.postgresql.org/message-id/202310071354.yljfgk2jgvvr%40alvherre.pgsql>
Precedence: bulk

On 2023-Oct-06, Andres Freund wrote:

> > +json_query_behavior:
> > +			ERROR_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_ERROR, NULL, @1); }
> > +			| NULL_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_NULL, NULL, @1); }
> > +			| DEFAULT a_expr	{ $$ = makeJsonBehavior(JSON_BEHAVIOR_DEFAULT, $2, @1); }
> > +			| EMPTY_P ARRAY	{ $$ = makeJsonBehavior(JSON_BEHAVIOR_EMPTY_ARRAY, NULL, @1); }
> > +			| EMPTY_P OBJECT_P	{ $$ = makeJsonBehavior(JSON_BEHAVIOR_EMPTY_OBJECT, NULL, @1); }
> > +			/* non-standard, for Oracle compatibility only */
> > +			| EMPTY_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_EMPTY_ARRAY, NULL, @1); }
> > +		;
> 
> > +json_exists_behavior:
> > +			ERROR_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_ERROR, NULL, @1); }
> > +			| TRUE_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_TRUE, NULL, @1); }
> > +			| FALSE_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_FALSE, NULL, @1); }
> > +			| UNKNOWN		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_UNKNOWN, NULL, @1); }
> > +		;
> > +
> > +json_value_behavior:
> > +			NULL_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_NULL, NULL, @1); }
> > +			| ERROR_P		{ $$ = makeJsonBehavior(JSON_BEHAVIOR_ERROR, NULL, @1); }
> > +			| DEFAULT a_expr	{ $$ = makeJsonBehavior(JSON_BEHAVIOR_DEFAULT, $2, @1); }
> > +		;
> 
> This also seems like it could use some dedup.

Yeah, I was looking at this the other day and thinking that we should
just have a single json_behavior that's used by all these productions;
at runtime we can check whether a value has been used that's improper
for that particular node, and error out with a syntax error or some
such.

Other parts of the grammar definitely needs more work, too.  It appears
to me that they were written by looking at what the standard says, more
or less literally.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"Someone said that it is at least an order of magnitude more work to do
production software than a prototype. I think he is wrong by at least
an order of magnitude."                              (Brian Kernighan)