Re: RangeTblEntry.inh vs. RTE_SUBQUERY

On 23.02.24 16:19, Tom Lane wrote:
> Dean Rasheed <dean.a.rasheed@gmail.com> writes:
>> On Fri, 23 Feb 2024 at 14:35, Peter Eisentraut <peter@eisentraut.org> wrote:
>>> Various code comments say that the RangeTblEntry field inh may only be
>>> set for entries of kind RTE_RELATION.
> 
>> Yes, it's explained a bit more clearly/accurately in expand_inherited_rtentry():
> 
>>   * "inh" is only allowed in two cases: RELATION and SUBQUERY RTEs.
> 
> Yes.  The latter has been accurate for a very long time, so I'm
> surprised that there are any places that think otherwise.  We need
> to fix them --- where did you see this exactly?

In nodes/parsenodes.h, it says both

     This *must* be false for RTEs other than RTE_RELATION entries.

and also puts it under

     Fields valid in all RTEs:

which are both wrong on opposite ends of the spectrum.

I think it would make more sense to group inh under "Fields valid for a 
plain relation RTE" and then explain the exception for subqueries, like 
it is done for several other fields.

See attached patch for a proposal.  (I also shuffled a few fields around 
to make the order a bit more logical.)