Message-ID: <efb33bee-145d-95a8-1048-2e7b8f282e2c@postgrespro.ru>
Date: Mon, 27 Feb 2023 11:23:57 +0500
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Subject: Re: Clause accidentally pushed down ( Possible bug in Making Vars
 outer-join aware)
To: Richard Guo <guofenglinux@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
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From: Andrey Lepikhov <a.lepikhov@postgrespro.ru>
Organization: Postgres Professional
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On 23/2/2023 11:36, Richard Guo wrote:
> I've realized this hack is not correct :-(.  References to A Vars and B
> Vars in higher qual levels do not need this adjustment.  So this code
> change would add unnecessary relids for clauses that involve A Vars or B
> Vars but not C Vars, resulting them being placed at higher place than
> needed.
> 
> Maybe what we need is to add in commute_below_l (assuming it has been
> recorded in SpecialJoinInfo) rather than commute_below of outer joins
> mentioned within the clause?
Doing a comparison of pg15 and master initsplan.c I found that a clear 
and documented algorithm for delaying the application of a qual is lost 
or replaced with some commute_* fields.
It is not clear how we guarantee correct application delay of a qual. 
Which part of the code implements it now?

-- 
regards,
Andrey Lepikhov
Postgres Professional