Horton

Re: remaining sql/json patches

amit <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Himanshu Upadhyaya <upadhyaya.himanshu@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Erik Rijkers <er@xs4all.nl>, jian he <jian.universality@gmail.com>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-03-07T12:06:08Z
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, Mar 7, 2024 at 8:13 PM Tomas Vondra
<tomas.vondra@enterprisedb.com> wrote:
> On 3/7/24 06:18, Himanshu Upadhyaya wrote:

Thanks Himanshu for the testing.

> > On Wed, Mar 6, 2024 at 9:04 PM Tomas Vondra <tomas.vondra@enterprisedb.com>
> > wrote:
> >>
> >> I'm pretty sure this is the correct & expected behavior. The second
> >> query treats the value as string (because that's what should happen for
> >> values in double quotes).
> >>
> >>  ok, Then why does the below query provide the correct conversion, even if
> > we enclose that in double quotes?
> > ‘postgres[102531]=#’SELECT * FROM JSON_TABLE(jsonb '{
> >          "id" : "1234567890",
> >          "FULL_NAME" : "JOHN DOE"}',
> >                 '$'
> >                 COLUMNS(
> >                      name varchar(20) PATH 'lax $.FULL_NAME',
> >                      id int PATH 'lax $.id'
> >       )
> >    )
> > ;
> >    name   |     id
> > ----------+------------
> >  JOHN DOE | 1234567890
> > (1 row)
> >
> > and for bigger input(string) it will leave as empty as below.
> > ‘postgres[102531]=#’SELECT * FROM JSON_TABLE(jsonb '{
> >          "id" : "12345678901",
> >          "FULL_NAME" : "JOHN DOE"}',
> >                 '$'
> >                 COLUMNS(
> >                      name varchar(20) PATH 'lax $.FULL_NAME',
> >                      id int PATH 'lax $.id'
> >       )
> >    )
> > ;
> >    name   | id
> > ----------+----
> >  JOHN DOE |
> > (1 row)
> >
> > seems it is not something to do with data enclosed in double quotes but
> > somehow related with internal casting it to integer and I think in case of
> > bigger input it is not able to cast it to integer(as defined under COLUMNS
> > as id int PATH 'lax $.id')
> >
> > ‘postgres[102531]=#’SELECT * FROM JSON_TABLE(jsonb '{
> >          "id" : "12345678901",
> >          "FULL_NAME" : "JOHN DOE"}',
> >                 '$'
> >                 COLUMNS(
> >                      name varchar(20) PATH 'lax $.FULL_NAME',
> >                      id int PATH 'lax $.id'
> >       )
> >    )
> > ;
> >    name   | id
> > ----------+----
> >  JOHN DOE |
> > (1 row)
> > )
> >
> > if it is not able to represent it to integer because of bigger input, it
> > should error out with a similar error message instead of leaving it empty.
> >
> > Thoughts?
> >
>
> Ah, I see! Yes, that's a bit weird. Put slightly differently:
>
> test=# SELECT * FROM JSON_TABLE(jsonb '{"id" : "2000000000"}',
>                 '$' COLUMNS(id int PATH '$.id'));
>      id
> ------------
>  2000000000
> (1 row)
>
> Time: 0.248 ms
> test=# SELECT * FROM JSON_TABLE(jsonb '{"id" : "3000000000"}',
>                 '$' COLUMNS(id int PATH '$.id'));
>  id
> ----
>
> (1 row)
>
> Clearly, when converting the string literal into int value, there's some
> sort of error handling that realizes 3B overflows, and returns NULL
> instead. I'm not sure if this is intentional.

Indeed.

This boils down to the difference in the cast expression chosen to
convert the source value to int in the two cases.

The case where the source value has no quotes, the chosen cast
expression is a FuncExpr for function numeric_int4(), which has no way
to suppress errors.  When the source value has quotes, the cast
expression is a CoerceViaIO expression, which can suppress the error.
The default behavior is to suppress the error and return NULL, so the
correct behavior is when the source value has quotes.

I think we'll need either:

* fix the code in 0001 to avoid getting numeric_int4() in this case,
and generally cast functions that don't have soft-error handling
support, in favor of using IO coercion.
* fix FuncExpr (like CoerceViaIO) to respect SQL/JSON's request to
suppress errors and fix downstream functions like numeric_int4() to
comply by handling errors softly.

I'm inclined to go with the 1st option as we already have the
infrastructure in place -- input functions can all handle errors
softly.

For the latter, it uses numeric_int4() which doesn't support
soft-error handling, so throws the error.  With quotes, the


--
Thanks, Amit Langote

--
Thanks, Amit Langote