Re: jsonb subscript operator returns null when key is fetched from table - Mailing list pgsql-bugs

"David G. Johnston" <david.g.johnston@gmail.com> writes:
> Someone more experienced than I will need to actually do the debugging work
> though; hoping this reply will be seen by one of them.

Meh.  Somebody was cavalier about detoasting the subscript:

            jbvp = getKeyJsonValueFromContainer(container,
                                                VARDATA(path[i]),
                                                VARSIZE(path[i]) - VARHDRSZ,
                                                NULL);

Neither VARDATA nor VARSIZE are valid to apply to an arbitrary datum.
Apparently, nobody has ever tested this with a subscript value fetched
straight from disk :-(.  The given example accidentally works with
a NOT MATERIALIZED CTE because the whole thing gets stepwise folded
to constants.  Likewise, the expression with || accidentally works
because concatenation always yields a non-toasted result.

            regards, tom lane