Re: SQL/JSON json_table plan clause - Mailing list pgsql-hackers

On Fri, Jul 10, 2026 at 6:48 PM Thom Brown <thom@linux.com> wrote:
>
> On Thu, 9 Jul 2026 at 21:28, Thom Brown <thom@linux.com> wrote:
> >
> > On Thu, 9 Jul 2026 at 20:52, Alexander Korotkov <aekorotkov@gmail.com> wrote:
> > >
> > > Hi, Thom!
> > >
> > > On Thu, Jul 9, 2026 at 7:12 PM Thom Brown <thom@linux.com> wrote:
> > > > On Wed, 8 Jul 2026 at 18:04, Alexander Korotkov <aekorotkov@gmail.com> wrote:
> > > > >
> > > > > On Wed, Jul 8, 2026 at 6:35 PM Nikita Malakhov <hukutoc@gmail.com> wrote:
> > > > > > Alexander, thank you for your participation. I am very sorry, I've seen your previous
> > > > > > email but was busy with other tasks and didn't have time to work on your notes.
> > > > > > Thank you very much!
> > > > >
> > > > > OK, no problem.  Are you good with the current shape of the patch?
> > > >
> > > > I've been giving this a test drive. I saw that this has been
> > > > committed, and re-tested against that, and the issues I identified
> > > > (unless I've misunderstood some functionality) seem to have survived.
> > >
> > > I tried my best to check if all the critics is addressed.  SQL/JSON patches
> > > go through so many threads.  Sorry that I missed your valuable insights.
> >
> > You didn't miss anything from me, so nothing to be sorry about. I just
> > meant I retested the issues I had found against the commit to see if
> > they had been fixed prior to submitting them. I hadn't raised them
> > prior to today.
> >
> > > > First, doesn't this need a catversion bump? This adds fields to
> > > > existing node types.
> > >
> > > Thank you for noticing, catversion is bumped.
> > >
> > > > I only get the first column from the following. The second one
> > > > disappears without error:
> > > >
> > > > SELECT * FROM JSON_TABLE(
> > > >   jsonb '[{"x":[1],"y":[2]}]', '$[*]' AS p0
> > > >   COLUMNS (
> > > >     NESTED PATH '$.x[*]' AS json_table_path_0 COLUMNS (x int PATH '$'),
> > > >     NESTED PATH '$.y[*]' COLUMNS (y int PATH '$')
> > > >   )
> > > >   PLAN (p0 OUTER json_table_path_0)
> > > > ) jt;
> > > >  x
> > > > ---
> > > >  1
> > > > (1 row)
> > >
> > > Yes, there is a bug in assignment of generated names.  Fixed in 0003.
> > >
> > > > I have the following view:
> > > > CREATE VIEW v_chain AS
> > > > SELECT * FROM JSON_TABLE(
> > > >   jsonb '[{"x": [{"y": [1,2]}]}]', '$[*]' AS p0
> > > >   COLUMNS ( NESTED PATH '$.x[*]' AS p1 COLUMNS (
> > > >    NESTED PATH '$.y[*]' AS p11 COLUMNS ( y int PATH '$' ) ) )
> > > >   PLAN (p0 OUTER (p1 INNER p11))
> > > > ) jt;
> > > >
> > > > When I dump it, I get:
> > > >
> > > > CREATE VIEW public.v_chain AS
> > > >  SELECT y
> > > >    FROM JSON_TABLE(
> > > >         '[{"x": [{"y": [1, 2]}]}]'::jsonb, '$[*]' AS p0
> > > >         COLUMNS (
> > > >             NESTED PATH '$."x"[*]' AS p1
> > > >             COLUMNS (
> > > >                 NESTED PATH '$."y"[*]' AS p11
> > > >                 COLUMNS (
> > > >                     y integer PATH '$'
> > > >                 )
> > > >             )
> > > >         )
> > > >         PLAN (p0 OUTER p1 INNER p11)
> > > >     ) jt;
> > > >
> > > > The parentheses around "p1 INNER p11" aren't preserved.
> > >
> > > Yes, there is a bug in the deparsing.  0002 fixes that.
> > >
> > > > Another dump issue with the following:
> > > >
> > > > CREATE VIEW v_onempty AS SELECT * FROM JSON_TABLE(
> > > >   jsonb '{}', '$' AS p0
> > > >   COLUMNS ( a int PATH '$.nosuch' ERROR ON EMPTY )
> > > >   ERROR ON ERROR
> > > > ) jt;
> > > >
> > > > This dumps as:
> > > >
> > > > CREATE VIEW public.v_onempty AS
> > > >  SELECT a
> > > >    FROM JSON_TABLE(
> > > >             '{}'::jsonb, '$' AS p0
> > > >             COLUMNS (
> > > >                 a integer PATH '$."nosuch"'
> > > >             ) ERROR ON ERROR
> > > >         ) jt;
> > > >
> > > > It's lost "ERROR ON EMPTY".
> > > >
> > > >
> > > > Another example:
> > > >
> > > > SELECT * FROM JSON_TABLE(jsonb '"mystring"', '$'
> > > >   COLUMNS (a int PATH '$')
> > > >   ERROR ON ERROR
> > > > ) jt;
> > > >
> > > > This gives me:
> > > >
> > > > ERROR:  invalid input syntax for type integer: "mystring"
> > > >
> > > > But the documentation says that the table-level clause "does not
> > > > affect the errors that occur when evaluating columns". Am I missing
> > > > something here?
> > >
> > > I've rechecked with SQL 2023 standard.  AFAICS, ON ERROR clause should
> > > be propagated from table to column.  We don't propagate it, so that must be
> > > a bug since PG 17.  But this patch shouldn't try to change it, it's out of scope.
> > > 0001 reverts attempt to change ON ERROR handling (this also fixes the case
> > > about of invalid dumpinged).  I think we need to consider this subject separately.
> >
> > Yeah, I haven't exercised JSON_TABLE enough since release, so I'm
> > clearly late in hitting this.
> >
> > Thanks for the fixes. I'll try to get round to testing them tomorrow
> > unless someone beats me to it.
>
> Attached are some documentation fixes.

Good, I've added them to my patchset.  I see you moved OUTER to come
before INNER.  I made the same reordering in other places for
consistency.

------
Regards,
Alexander Korotkov
Supabase