Horton

Re: remaining sql/json patches

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Himanshu Upadhyaya <upadhyaya.himanshu@gmail.com>, Erik Rijkers <er@xs4all.nl>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-04-04T08:24:01Z
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 Thu, Apr 4, 2024 at 3:50 PM jian he <jian.universality@gmail.com> wrote:
>
> On Thu, Apr 4, 2024 at 2:41 PM jian he <jian.universality@gmail.com> wrote:
> >
> > On Wed, Apr 3, 2024 at 8:39 PM Amit Langote <amitlangote09@gmail.com> wrote:
> > >
> > > Attached updated patches.  I have addressed your doc comments on 0001,
> > > but not 0002 yet.

hi
some doc issue about v49, 0002.
+  Each
+  <literal>NESTED PATH</literal> clause can be used to generate one or more
+  columns using the data from a nested level of the row pattern, which can be
+  specified using a <literal>COLUMNS</literal> clause.
 maybe change to

+  Each
+  <literal>NESTED PATH</literal> clause can be used to generate one or more
+  columns using the data from an upper nested level of the row
pattern, which can be
+  specified using a <literal>COLUMNS</literal> clause


+   Child
+   columns may themselves contain a <literal>NESTED PATH</literal>
+   specifification thus allowing to extract data located at arbitrary nesting
+   levels.
maybe change to
+  Child
+  columns themselves  may contain a <literal>NESTED PATH</literal>
+   specification thus allowing to extract data located at any arbitrary nesting
+   level.


+</screen>
+     </para>
+     <para>
+      The following is a modified version of the above query to show the usage
+      of <literal>NESTED PATH</literal> for populating title and director
+      columns, illustrating how they are joined to the parent columns id and
+      kind:
+<screen>
+SELECT jt.* FROM
+ my_films,
+ JSON_TABLE ( js, '$.favorites[*] ? (@.films[*].director == $filter)'
+   PASSING 'Alfred Hitchcock' AS filter
+   COLUMNS (
+    id FOR ORDINALITY,
+    kind text PATH '$.kind',
+    NESTED PATH '$.films[*]' COLUMNS (
+      title text FORMAT JSON PATH '$.title' OMIT QUOTES,
+      director text PATH '$.director' KEEP QUOTES))) AS jt;
+ id |   kind   |  title  |      director
+----+----------+---------+--------------------
+  1 | horror   | Psycho  | "Alfred Hitchcock"
+  2 | thriller | Vertigo | "Alfred Hitchcock"
+(2 rows)
+</screen>
+     </para>
+     <para>
+      The following is the same query but without the filter in the root
+      path:
+<screen>
+SELECT jt.* FROM
+ my_films,
+ JSON_TABLE ( js, '$.favorites[*]'
+   COLUMNS (
+    id FOR ORDINALITY,
+    kind text PATH '$.kind',
+    NESTED PATH '$.films[*]' COLUMNS (
+      title text FORMAT JSON PATH '$.title' OMIT QUOTES,
+      director text PATH '$.director' KEEP QUOTES))) AS jt;
+ id |   kind   |      title      |      director
+----+----------+-----------------+--------------------
+  1 | comedy   | Bananas         | "Woody Allen"
+  1 | comedy   | The Dinner Game | "Francis Veber"
+  2 | horror   | Psycho          | "Alfred Hitchcock"
+  3 | thriller | Vertigo         | "Alfred Hitchcock"
+  4 | drama    | Yojimbo         | "Akira Kurosawa"
+(5 rows)
 </screen>

just found out that the query and the query's output condensed together.
in https://www.postgresql.org/docs/current/tutorial-window.html
the query we use <programlisting>, the output we use <screen>.
maybe we can do it the same way,
or we could just have one or two empty new lines separate them.
we have the similar problem in v49, 0001.