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Re: SQL/JSON: functions

Peter Eisentraut <peter.eisentraut@enterprisedb.com>

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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
To: Himanshu Upadhyaya <upadhyaya.himanshu@gmail.com>, Andrew Dunstan <andrew@dunslane.net>
Cc: Nikita Glukhov <n.gluhov@postgrespro.ru>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Dmitry Dolgov <9erthalion6@gmail.com>, Oleg Bartunov <obartunov@postgrespro.ru>, Erik Rijkers <er@xs4all.nl>
Date: 2021-12-09T15:08:50Z
Lists: pgsql-hackers 
On 09.12.21 15:04, Himanshu Upadhyaya wrote:
> 1)
> Why we don't support KEY(however is optional as per SQL standard) keyword?
> SELECT JSON_OBJECT(KEY 'a' VALUE '123');
> ERROR:  type "key" does not exist
> LINE 1: SELECT JSON_OBJECT(KEY 'a' VALUE '123');
> 
> ORACLE is supporting the above syntax.
> 
> I can see TODO as below
> +json_name_and_value:
> +/* TODO This is not supported due to conflicts
> +                       KEY c_expr VALUE_P json_value_expr %prec POSTFIXOP
> +                               { $$ = makeJsonKeyValue($2, $4); }
> +                       |
> +*/
> 
> but still not very clear what kind of conflict we are mentioning here, 
> also any plan of finding a solution to that conflict?

The conflict is this:

Consider in subclause 6.33, “<JSON value constructor>”:

<JSON name and value> ::= [ KEY ] <JSON name> VALUE <JSON input expression>
| ...

Because KEY is a <non-reserved word>, this creates an ambiguity. For 
example:

key(x) VALUE foo

could be

KEY x VALUE foo

with KEY being the key word and “x” (a <column reference>) as “<JSON 
name>”, or

KEY key(x) VALUE foo

with “key(x)” (a <routine invocation>) as “<JSON name>”.

In existing implementations, KEY is resolved as a keyword.  So if you 
can figure out a way to implement that, go ahead, but I imagine it might 
be tricky.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. JSON_TABLE: Add support for NESTED paths and columns

  2. Add basic JSON_TABLE() functionality

  3. Add SQL/JSON query functions

  4. Add soft error handling to some expression nodes

  5. Adjust populate_record_field() to handle errors softly

  6. Refactor code used by jsonpath executor to fetch variables

  7. Add more SQL/JSON constructor functions

  8. SQL/JSON: support the IS JSON predicate

  9. SQL/JSON: add standard JSON constructor functions

  10. Improve readability of SQL/JSON documentation.

  11. Documentation for SQL/JSON features

  12. RETURNING clause for JSON() and JSON_SCALAR()

  13. SQL JSON functions

  14. SQL/JSON query functions

  15. IS JSON predicate

  16. SQL/JSON constructors

  17. Common SQL/JSON clauses

  18. Doc: remove obsolete entries in table of BRIN strategy numbers.

  19. Doc: standardize markup a bit more.

  20. Make pg_regress.c unset PGDATABASE during make installcheck.

  21. Fix handling of GENERATED columns in CREATE TABLE LIKE INCLUDING DEFAULTS.