Horton

Re: remaining sql/json patches

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Andy Fan <zhihuifan1213@163.com>
Cc: Amit Langote <amitlangote09@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Erik Rijkers <er@xs4all.nl>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org, Peter Eisentraut <peter@eisentraut.org>
Date: 2024-03-07T04:08:21Z
Lists: pgsql-hackers

Commits

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

  1. SQL/JSON: Various improvements to SQL/JSON query function docs

  2. SQL/JSON: Fix some obsolete comments.

  3. SQL/JSON: Fix issues with DEFAULT .. ON ERROR / EMPTY

  4. JSON_TABLE: Add support for NESTED paths and columns

  5. Fix JsonExpr deparsing to emit QUOTES and WRAPPER correctly

  6. Fix typo introduced in 6185c9737

  7. Add basic JSON_TABLE() functionality

  8. Avoid splitting errmsg string to span multiple lines

  9. Add SQL/JSON query functions

  10. Implement various jsonpath methods

  11. Add soft error handling to some expression nodes

  12. Adjust populate_record_field() to handle errors softly

  13. Refactor code used by jsonpath executor to fetch variables

  14. Test EXPLAIN (FORMAT JSON) ... XMLTABLE

  15. Simplify productions for FORMAT JSON [ ENCODING name ]

  16. Add trailing commas to enum definitions

  17. doc: add missing <returnvalue> and whitespace

  18. Add more SQL/JSON constructor functions

  19. Rename a nonterminal used in SQL/JSON grammar

  20. Some refactoring to export json(b) conversion functions

  21. Don't include CaseTestExpr in JsonValueExpr.formatted_expr

  22. Code review for commit b6e1157e7d

  23. Pass constructName to transformJsonValueExpr()

  24. Unify JSON categorize type API and export for external use

  25. Make some indentation in gram.y consistent

  26. Allow most keywords to be used as column labels without requiring AS.

  27. Reduce size of backend scanner's tables.

  28. Use perfect hashing, instead of binary search, for keyword lookup.

On Tue, Mar 5, 2024 at 12:38 PM Andy Fan <zhihuifan1213@163.com> wrote:
>
>
> In the commit message of 0001, we have:
>
> """
> Both JSON_VALUE() and JSON_QUERY() functions have options for
> handling EMPTY and ERROR conditions, which can be used to specify
> the behavior when no values are matched and when an error occurs
> during evaluation, respectively.
>
> All of these functions only operate on jsonb values. The workaround
> for now is to cast the argument to jsonb.
> """
>
> which is not clear for me why we introduce JSON_VALUE() function, is it
> for handling EMPTY or ERROR conditions? I think the existing cast
> workaround have a similar capacity?
>

I guess because it's in the standard.
but I don't see individual sql standard Identifier, JSON_VALUE in
sql_features.txt
I do see JSON_QUERY.
mysql also have JSON_VALUE, [1]

EMPTY, ERROR: there is a standard Identifier: T825: SQL/JSON: ON EMPTY
and ON ERROR clauses

[1] https://dev.mysql.com/doc/refman/8.0/en/json-search-functions.html#function_json-value