Date: Tue, 5 Oct 2021 12:19:22 -0500
From: Jaime Casanova <jcasanov@systemguards.com.ec>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
	Anastasia Lubennikova <a.lubennikova@postgrespro.ru>,
	Pg Hackers <pgsql-hackers@lists.postgresql.org>,
	Richard Guo <riguo@pivotal.io>, ashutosh.bapat@enterprisedb.com
Subject: Re: A problem about partitionwise join
Message-ID: <20211005171922.GB28628@ahch-to>
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On Wed, Jul 21, 2021 at 04:44:53PM +0800, Richard Guo wrote:
> On Fri, Nov 27, 2020 at 8:05 PM Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
> wrote:
> 
> >
> > In the example you gave earlier, the equi join on partition key was
> > there but it was replaced by individual constant assignment clauses.
> > So if we keep the original restrictclause in there with a new flag
> > indicating that it's redundant, have_partkey_equi_join will still be
> > able to use it without much change. Depending upon where all we need
> > to use avoid restrictclauses with the redundant flag, this might be an
> > easier approach. However, with Tom's idea partition-wise join may be
> > used even when there is no equi-join between partition keys but there
> > are clauses like pk = const for all tables involved and const is the
> > same for all such tables.
> >
> 
> Correct. So with Tom's idea partition-wise join can cope with clauses
> such as 'foo.k1 = bar.k1 and foo.k2 = 16 and bar.k2 = 16'.
> 
> 
> >
> > In the spirit of small improvement made to the performance of
> > have_partkey_equi_join(), pk_has_clause should be renamed as
> > pk_known_equal and pks_known_equal as num_equal_pks.
> >
> 
> Thanks for the suggestion. Will do that in the new version of patch.
> 

Hi Richard,

We are marking this CF entry as "Returned with Feedback", which means
you are encouraged to send a new patch (and create a new entry for a
future CF for it) with the suggested changes.

-- 
Jaime Casanova
Director de Servicios Profesionales
SystemGuards - Consultores de PostgreSQL