Re: Weird special case in jsonb_concat()

so 19. 12. 2020 v 21:35 odesílatel Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> napsal:

> I wrote:
> > However, further experimentation found a case that fails:
> > regression=# select '3'::jsonb || '{}'::jsonb;
> > ERROR: invalid concatenation of jsonb objects
> > I wonder what is the point of this weird exception, and whether
> > whoever devised it can provide a concise explanation of what
> > they think the full behavior of "jsonb || jsonb" is. Why isn't
> > '[3, {}]' a reasonable result here, if the cases above are OK?
>
> Here is a proposed patch for that. It turns out that the third
> else-branch in IteratorConcat() already does the right thing, if
> we just remove its restrictive else-condition and let it handle
> everything except the two-objects and two-arrays cases. But it
> seemed to me that trying to handle both the object || array
> and array || object cases in that one else-branch was poorly
> thought out: only one line of code can actually be shared, and it
> took several extra lines of infrastructure to support the sharing.
> So I split those cases into separate else-branches.
>
> This also addresses the inadequate documentation that was the
> original complaint.
>
> Thoughts? Should we back-patch this? The existing behavior
> seems to me to be inconsistent enough to be arguably a bug,
> but we've not had field complaints saying "this should work".
>

+1

Pavel

> regards, tom lane
>
>