Re: checking my understanding of TupleDesc

Andres Freund <andres@anarazel.de> writes:
> On 2019-11-12 17:39:20 -0500, Tom Lane wrote:
>> There's a semi-exception, which is that the planner might decide that we
>> can skip a projection step for the output of a table scan node, in which
>> case dropped columns would be included in its output.  But that would only
>> be true if there are upper plan nodes that are doing some projections of
>> their own.  The final query output will definitely not have them.

> I *think* we don't even do that, because build_physical_tlist() bails
> out if there's a dropped (or missing) column.

Ah, right.  Probably because we need to insist on every column of an
execution-time tupdesc having a valid atttypid ... although I wonder,
is that really necessary?

            regards, tom lane