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Date: Thu, 7 Mar 2024 16:56:13 +0100
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Subject: Re: RangeTblEntry.inh vs. RTE_SUBQUERY
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From: Peter Eisentraut <peter@eisentraut.org>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
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On 03.03.24 11:02, Peter Eisentraut wrote:
> 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.

I have committed the patches for this discussion.

Related discussion will continue at 
https://www.postgresql.org/message-id/flat/4b27fc50-8cd6-46f5-ab20-88dbaadca645@eisentraut.org 
/ https://commitfest.postgresql.org/47/4697/ .