Date: Sun, 10 May 2020 19:36:58 +0200
From: Dmitry Dolgov <9erthalion6@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Floris Van Nee <florisvannee@optiver.com>,
	Dilip Kumar <dilipbalaut@gmail.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Peter Geoghegan <pg@bowt.ie>,
	Jesper Pedersen <jesper.pedersen@redhat.com>,
	Alvaro Herrera <alvherre@2ndquadrant.com>,
	Thomas Munro <thomas.munro@gmail.com>,
	James Coleman <jtc331@gmail.com>,
	Rafia Sabih <rafia.pghackers@gmail.com>,
	Jeff Janes <jeff.janes@gmail.com>,
	"bhushan.uparkar@gmail.com" <bhushan.uparkar@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Alexander Korotkov <a.korotkov@postgrespro.ru>
Subject: Re: Index Skip Scan
Message-ID: <20200510173658.kfmyzsrmcr2n3cre@localhost>
References: <20200325085100.5fixaiteuoln4f45@localhost>
 <CAFiTN-sgsxS7cXi0sd9UWmbSwjPc6+78rGa4SFfAxGfs5zj7Aw@mail.gmail.com>
 <20200405161029.fpqqll7xbgfqy5na@localhost>
 <CAFiTN-sRnYp7MkctzYakyjWRPQQHFzEAwKV8vwf+sUgA+8JtQw@mail.gmail.com>
 <80ef5f0744f542b18e508fb589a6425a@opammb0562.comp.optiver.com>
 <CAFiTN-tp8S3BTwYXT33tnY=53fNCsS4ZZUjbEFtcJym1acoLeA@mail.gmail.com>
 <20200406163941.rh3okji2rhbnptyt@localhost>
 <8abe43ac82714c2f9044fb8bac0ebfd0@opammb0562.comp.optiver.com>
 <20200407194220.edf4nbi7l4cpxk4v@localhost>
 <CAApHDvquG6ZxcYO5s+qqVFnTYCC7Anm2YM9Ob2gw_pogBvw9bA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: 
 <CAApHDvquG6ZxcYO5s+qqVFnTYCC7Anm2YM9Ob2gw_pogBvw9bA@mail.gmail.com>
Precedence: bulk

Sorry for late reply.

> On Tue, Apr 14, 2020 at 09:19:22PM +1200, David Rowley wrote:
>
> I've not yet looked at the latest patch, but I did put some thoughts
> into an email on the other thread that's been discussing UniqueKeys
> [1].
>
> I'm keen to hear thoughts on the plan I mentioned over there.  Likely
> it would be best to discuss the specifics of what additional features
> we need to add to UniqueKeys for skip scans over here, but discuss any
> chances which affect both patches over there.  We certainly can't have
> two separate implementations of UniqueKeys, so I believe the skip
> scans UniqueKeys patch should most likely be based on the one in [1]
> or some descendant of it.
>
> [1] https://www.postgresql.org/message-id/CAApHDvpx1qED1uLqubcKJ=oHatCMd7pTUKkdq0B72_08nbR3Hw@mail.gmail.com

Yes, I've come to the same conclusion, although I have my concerns about
having such a dependency between patches. Will look at the suggested
patches soon.