Feedback-ID: ie0a040ee:Fastmail
Message-ID: <09a4b507-1c38-4eca-81bb-296245175893@eisentraut.org>
Date: Sun, 3 Mar 2024 11:02:48 +0100
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: RangeTblEntry.inh vs. RTE_SUBQUERY
Content-Language: en-US
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>
References: <6c1fbccc-85c8-40d3-b08b-4f47f2093711@eisentraut.org>
 <CAEZATCXZP9dd4oym=nLzkHswjfBcY6-Xe4RH+v+YLC0jiKR30Q@mail.gmail.com>
 <814829.1708701565@sss.pgh.pa.us>
 <54faad3d-d604-4ef6-9e78-b055861f54cd@eisentraut.org>
 <2718281.1709230491@sss.pgh.pa.us>
From: Peter Eisentraut <peter@eisentraut.org>
In-Reply-To: <2718281.1709230491@sss.pgh.pa.us>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: <https://www.postgresql.org/message-id/09a4b507-1c38-4eca-81bb-296245175893%40eisentraut.org>
Precedence: bulk

On 29.02.24 19:14, Tom Lane wrote:
> Peter Eisentraut <peter@eisentraut.org> writes:
>> In nodes/parsenodes.h, it says both
>>       This *must* be false for RTEs other than RTE_RELATION entries.
> 
> Well, that's true in the parser ...
> 
>> 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.
> 
> Dunno.  The adjacent "lateral" field is also used for only selected
> RTE kinds.

The section is

     /*
      * Fields valid in all RTEs:
      */
     Alias      *alias;          /* user-written alias clause, if any */
     Alias      *eref;           /* expanded reference names */
     bool        lateral;        /* subquery, function, or values is 
LATERAL? */
     bool        inh;            /* inheritance requested? */
     bool        inFromCl;       /* present in FROM clause? */
     List       *securityQuals;  /* security barrier quals to apply, if 
any */

According to my testing, lateral is used for RTE_RELATION, RTE_SUBQUERY, 
RTE_FUNCTION, RTE_TABLEFUNC, RTE_VALUES, which is 5 out of 9 possible. 
So I think it might be okay to relabel that section (in actuality or 
mentally) as "valid in several/many/most RTEs".

But I'm not sure what reason there would be for having inh there, which 
is better described as "valid for RTE_RELATION, but also borrowed by 
RTE_SUBQUERY", which is pretty much exactly what is the case for relid, 
relkind, etc.