Horton

Re: remaining sql/json patches

amit <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Erik Rijkers <er@xs4all.nl>
Cc: jian he <jian.universality@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Andrew Dunstan <andrew@dunslane.net>
Date: 2023-07-18T09:11:06Z
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.

Attachments

Hi,

On Mon, Jul 17, 2023 at 4:14 PM Erik Rijkers <er@xs4all.nl> wrote:
> Op 7/17/23 om 07:00 schreef jian he:
> > hi.
> > seems there is no explanation about, json_api_common_syntax in
> > functions-json.html
> >
> > I can get json_query full synopsis from functions-json.html as follows:
> > json_query ( context_item, path_expression [ PASSING { value AS
> > varname } [, ...]] [ RETURNING data_type [ FORMAT JSON [ ENCODING UTF8
> > ] ] ] [ { WITHOUT | WITH { CONDITIONAL | [UNCONDITIONAL] } } [ ARRAY ]
> > WRAPPER ] [ { KEEP | OMIT } QUOTES [ ON SCALAR STRING ] ] [ { ERROR |
> > NULL | EMPTY { [ ARRAY ] | OBJECT } | DEFAULT expression } ON EMPTY ]
> > [ { ERROR | NULL | EMPTY { [ ARRAY ] | OBJECT } | DEFAULT expression }
> > ON ERROR ])
> >
> > seems doesn't  have a full synopsis for json_table? only partial one
> > by  one explanation.

I looked through the history of the docs portion of the patch and it
looks like the synopsis for JSON_TABLE(...) used to be there but was
taken out during one of the doc reworks [1].

I've added it back in the patch as I agree that it would help to have
it.   Though, I am not totally sure where I've put it is the right
place for it.  JSON_TABLE() is a beast that won't fit into the table
that JSON_QUERY() et al are in, so maybe that's how it will have to
be?  I have no better idea.

> FWIW, Re: json_api_common_syntax
...
> An (old) pdf that I have (ISO/IEC TR 19075-6 First edition 2017-03)
> contains the below specification.  It's probably the source of the
> particular term.  It's easy to see how it maps onto the current v7
> SQL/JSON implementation.   (I don't know if it has changed in later
> incarnations.)
>
>
> ------ 8< ------------
> 5.2  JSON API common syntax
>
> The SQL/JSON query functions all need a path specification, the JSON
> value to be input to that path specification for querying and
> processing, and optional parameter values passed to the path
> specification. They use a common syntax:
>
> <JSON API common syntax> ::=
>    <JSON context item> <comma> <JSON path specification>
>       [ AS <JSON table path name> ]
>       [ <JSON passing clause> ]
>
> <JSON context item> ::=
>     <JSON value expression>
>
> <JSON path specification> ::=
>    <character string literal>
>
> <JSON passing clause> ::=
>     PASSING <JSON argument> [ { <comma> <JSON argument> } ]
>
> <JSON argument> ::=
>     <JSON value expression> AS <identifier>
>
> ------ 8< ------------
>
> And yes, we might need a readable translation of that in the docs
> although it might be easier to just get get rid of the term
> 'json_api_common_syntax'.

I found a patch proposed by Andrew Dunstan in the v15 dev cycle to get
rid of the term in the JSON_TABLE docs that Erik seemed to agree with
[2], so I've applied it.

Attached updated patches.  In 0002, I removed the mention of the
RETURNING clause in the JSON(), JSON_SCALAR() documentation, which I
had forgotten to do in the last version which removed its support in
code.

I think 0001 looks ready to go.  Alvaro?

Also, I've been wondering if it isn't too late to apply the following
to v16 too, so as to make the code look similar in both branches:

b6e1157e7d Don't include CaseTestExpr in JsonValueExpr.formatted_expr
785480c953 Pass constructName to transformJsonValueExpr()

--
Thanks, Amit Langote
EDB: http://www.enterprisedb.com

[1] https://www.postgresql.org/message-id/044204fa-738d-d89a-0e81-1c04696ba676%40dunslane.net
[2] https://www.postgresql.org/message-id/10c997db-9270-bdd5-04d5-0ffc1eefcdb7%40dunslane.net