Andres Freund <andres@anarazel.de> writes:
> On 2021-04-22 14:37:26 -0400, Tom Lane wrote:
>> OK, I could work with that. Shall we spell the error message the
>> same as if it really were a virtual slot, or does it need to be
>> different to avoid confusion?
> Hm. Seems like it'd be better to have a distinct error message? Feels
> like it'll often indicate separate issues whether a non-materialized
> heap slot or a virtual slot has its system columns accessed.
After thinking about it for a bit, I'm inclined to promote this to
a user-facing error, and have all the slot types report
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot retrieve a system column in this context")));
which is at least somewhat intelligible to end users. A developer
trying to figure out why it happened would resort to \errverbose or
more likely gdb in any case, so the lack of specificity doesn't
seem like a problem.
> Not entirely clear to me how we'd track whether we have valid system
> column data or not once materialized - which I think is why we
> historically had the cases where we returned bogus values.
Right, but with this fix we won't need to materialize.
regards, tom lane
