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>, Andres Freund <andres@anarazel.de>, Erik Rijkers <er@xs4all.nl>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-02-06T04:55:51Z
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, Jan 25, 2024 at 10:39 PM jian he <jian.universality@gmail.com> wrote:
>
> On Thu, Jan 25, 2024 at 7:54 PM Amit Langote <amitlangote09@gmail.com> wrote:
> >
> > >
> > > The problem with returning comp_domain_with_typmod from json_value()
> > > seems to be that it's using a text-to-record CoerceViaIO expression
> > > picked from JsonExpr.item_coercions, which behaves differently than
> > > the expression tree that the following uses:
> > >
> > > select ('abcd', 42)::comp_domain_with_typmod;
> > >    row
> > > ----------
> > >  (abc,42)
> > > (1 row)
> >
> > Oh, it hadn't occurred to me to check what trying to coerce a "string"
> > containing the record literal would do:
> >
> > select '(''abcd'', 42)'::comp_domain_with_typmod;
> > ERROR:  value too long for type character(3)
> > LINE 1: select '(''abcd'', 42)'::comp_domain_with_typmod;
> >
> > which is the same thing as what the JSON_QUERY() and JSON_VALUE() are
> > running into.  So, it might be fair to think that the error is not a
> > limitation of the SQL/JSON patch but an underlying behavior that it
> > has to accept as is.
> >
>
> Hi, I reconciled with these cases.
> What bugs me now is the first query of the following 4 cases (for comparison).
> SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING char(3) omit quotes);
> SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING char(3) keep quotes);
> SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING text omit quotes);
> SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING text keep quotes);
>

based on v39.
in ExecEvalJsonCoercion
coercion->targettypmod related function calls:
json_populate_type calls populate_record_field, then populate_scalar,
later will eventually call InputFunctionCallSafe.

so I make the following change:
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -4533,7 +4533,7 @@ ExecEvalJsonCoercion(ExprState *state, ExprEvalStep *op,
         * deed ourselves by calling the input function, that is, after removing
         * the quotes.
         */
-       if (jb && JB_ROOT_IS_SCALAR(jb) && coercion->omit_quotes)
+       if ((jb && JB_ROOT_IS_SCALAR(jb) && coercion->omit_quotes) ||
coercion->targettypmod != -1)

now the following two return the same result:  `[1,`
SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING char(3) omit quotes);
SELECT JSON_QUERY(jsonb '[1,2]', '$' RETURNING char(3) keep quotes);