Date: Wed, 22 Jan 2020 22:37:16 +0100
From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Floris Van Nee <florisvannee@Optiver.com>
Cc: Peter Geoghegan <pg@bowt.ie>,
	Jesper Pedersen <jesper.pedersen@redhat.com>,
	David Rowley <david.rowley@2ndquadrant.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.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 <bhushan.uparkar@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Alexander Korotkov <a.korotkov@postgrespro.ru>
Subject: Re: Index Skip Scan
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> On Wed, Jan 22, 2020 at 09:08:59PM +0000, Floris Van Nee wrote:
> > Note in particular that index scans cannot return the same index tuple twice -
> > - processing a page at a time ensures that that cannot happen.
> >
> > Can a loose index scan return the same tuple (i.e. a tuple with the same heap
> > TID) to the executor more than once?
> >
>
> The loose index scan shouldn't return a tuple twice. It should only be able to skip 'further', so that shouldn't be a problem.

Yes, it shouldn't happen.