Re: jsonb concatenate operator's semantics seem questionable

On Thu, May 21, 2015 at 2:25 PM, Andrew Dunstan <andrew@dunslane.net> wrote:
> This change really makes this set of jsonb features quite a bit more
> compelling. I'm glad I thought of it - wish I had done so earlier. So
> notwithstanding the controversy upthread, I think this is a good result.

I think that we should look into making jsonb support array-style
subscripting within updates (to update "nested subdatums" directly).
This would make the new concatenate operator a lot more compelling.
Also, UPDATE targetlists don't accept a table qualification in their
targetlist (for the assign-to column) because the parser similarly
needs to support updating composite type's "nested subdatums"
directly.

Having gone to the trouble of making the parser support this stuff (in
a way that makes us not follow the SQL standard in a couple of
places), we ought to have a similar capability for jsonb. I haven't
looked into it, but it seems like a good project for 9.6. I'm not
volunteering to undertake the project, though.
-- 
Peter Geoghegan