Horton

Re: remaining sql/json patches

amit <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Erik Rijkers <er@xs4all.nl>, jian he <jian.universality@gmail.com>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2023-12-20T08:36:25Z
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

On Thu, Dec 14, 2023 at 5:04 PM Amit Langote <amitlangote09@gmail.com> wrote:
> On Sat, Dec 9, 2023 at 2:30 AM Andres Freund <andres@anarazel.de> wrote:
> > On 2023-12-07 21:07:59 +0900, Amit Langote wrote:
> > > From 38b53297b2d435d5cebf78c1f81e4748fed6c8b6 Mon Sep 17 00:00:00 2001
> > > From: Amit Langote <amitlan@postgresql.org>
> > > Date: Wed, 22 Nov 2023 13:18:49 +0900
> > > Subject: [PATCH v30 2/5] Add soft error handling to populate_record_field()
> > >
> > > An uncoming patch would like the ability to call it from the
> > > executor for some SQL/JSON expression nodes and ask to suppress any
> > > errors that may occur.
> > >
> > > This commit does two things mainly:
> > >
> > > * It modifies the various interfaces internal to jsonfuncs.c to pass
> > >   the ErrorSaveContext around.
> > >
> > > * Make necessary modifications to handle the cases where the
> > >   processing is aborted partway through various functions that take
> > >   an ErrorSaveContext when a soft error occurs.
> > >
> > > Note that the above changes are only intended to suppress errors in
> > > the functions in jsonfuncs.c, but not those in any external functions
> > > that the functions in jsonfuncs.c in turn call, such as those from
> > > arrayfuncs.c.  It is assumed that the various populate_* functions
> > > validate the data before passing those to external functions.
> > >
> > > Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
> >
> > The code here is getting substantially more verbose / less readable.  I wonder
> > if there's something more general that could be improved to make this less
> > painful?
>
> Hmm, I can't think of anything short of a rewrite of the code under
> populate_record_field() so that any error-producing code is well
> isolated or adding a variant/wrapper with soft-error handling
> capabilities.  I'll give this some more thought, though I'm happy to
> hear ideas.

I looked at this and wasn't able to come up with alternative takes
that are better in terms of the verbosity/readability.  I'd still want
to hear if someone well-versed in the json(b) code has any advice.

I also looked at some commits touching src/backend/utils/adt/json*
files to add soft error handling and I can't help but notice that
those commits look not very different from this.  For example, commits
c60c9bad, 50428a30 contain changes like:

@@ -454,7 +474,11 @@ parse_array_element(JsonLexContext *lex,
JsonSemAction *sem)
        return result;

    if (aend != NULL)
-       (*aend) (sem->semstate, isnull);
+   {
+       result = (*aend) (sem->semstate, isnull);
+       if (result != JSON_SUCCESS)
+           return result;
+   }

Attached updated patches addressing jian he's comments, some minor
fixes, and commit message updates.



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