Re: jsonb subscript operator returns null when key is fetched from table

On Fri, Dec 9, 2022 at 1:35 PM exe-dealer <exe-dealer(at)yandex(dot)ru> wrote:

> jsonb subscript operator returns null when key is fetched from table.
>
> PostgreSQL 15.1 on x86_64-pc-linux-musl, compiled by gcc (Alpine
> 12.2.1_git20220924-r4) 12.2.1 20220924, 64-bit
>
> WITH cte AS MATERIALIZED (SELECT 'foo' k, '{"foo":"bar"}'::jsonb j)
> SELECT j[k], j[k || ''] FROM cte;
>
> -- returns
> -- null, "bar"
>
> -- expected
> -- "bar", "bar"
>

Thanks for the report. I can confirm that this is a problem in both v14
and v15.

To clarify the subject line - the issue manifests only if the CTE is
MATERIALIZED.

Someone more experienced than I will need to actually do the debugging work
though; hoping this reply will be seen by one of them.

David J.