Re: JSON_TABLE: table => column ON ERROR propagation

Hi!

Alexander, IMHO the 2nd option is the best. To revise queries for 2 versions
could involve a lot of work, testing and system behavior changes.

On Thu, Aug 6, 2026 at 7:01 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com>
wrote:

> Hi!
>
> While working on the JSON_TABLE PLAN clause [1], I found that our
> implementation of JSON_TABLE has a standard divergence. In our
> implementation, the table-level ON ERROR clause and the column-level
> ON ERROR clause are completely independent. But according to ISO/IEC
> 9075-2 2023, the table-level ON ERROR clause is propagated to the
> column level if the column doesn't have its own explicit ON ERROR
> clause.
>
> I can't share my copy of the standard, but I verified that Chapter
> 7.11 Syntax Rules 1) e) iv) and 1) f) xi) specify that if a column
> element lacks an ON ERROR clause and the table-level clause is ERROR
> ON ERROR, then ERROR ON ERROR applies to the column. Otherwise (no
> table-level clause or table-level clause is NULL ON ERROR), NULL ON
> ERROR applies to the column.
>
> For instance, this query returns NULL on the current master, but must
> error out according to the standard.
>
> SELECT * FROM JSON_TABLE(jsonb '"err"', '$' COLUMNS (a int PATH '$')
> ERROR ON ERROR) jt;
>
> I've drafted a patch that implements the behavior specified in the
> standard. That's not a very complicated patch, but I see a problem:
> JSON_TABLE was released in PostgreSQL 17, and this patch changes
> user-visible behavior.
>
> I see some options we can go ahead with:
> 1) Backpatch this to PostgreSQL 17, and issue release notes that users
> should check and revise their queries.
> 2) Patch only master, and issue the same notes for the PostgreSQL 20
> release.
> 3) Add the GUC controlling this behavior (I don't really like that).
>
> Any thoughts?
>
> Links.
> 1.
> https://www.postgresql.org/message-id/CAPpHfdt%3DLncQH9PAq9O8qO7KZcTT9rOsxLLanscRF7xDFvK8mA%40mail.gmail.com
>
> ------
> Regards,
> Alexander Korotkov
> Supabase
>

--
Regards,
Nikita Malakhov
Postgres Professional
The Russian Postgres Company
https://postgrespro.ru/