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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: 9erthalion6@gmail.com
Cc: florisvannee@optiver.com
Cc: jesper.pedersen@redhat.com
Cc: david.rowley@2ndquadrant.com
Cc: thomas.munro@gmail.com
Cc: jtc331@gmail.com
Cc: rafia.pghackers@gmail.com
Cc: jeff.janes@gmail.com
Cc: pg@bowt.ie
Cc: tomas.vondra@2ndquadrant.com
Cc: thomas.munro@enterprisedb.com
Cc: bhushan.uparkar@gmail.com
Cc: pgsql-hackers@postgresql.org
Cc: a.korotkov@postgrespro.ru
Subject: Re: Index Skip Scan
Date: Tue, 24 Sep 2019 09:06:27 -0300
Message-ID: <20190924120627.GA12454@alvherre.pgsql> (raw)
In-Reply-To: <20190924.174146.159197618.horikyota.ntt@gmail.com>

On 2019-Sep-24, Kyotaro Horiguchi wrote:

> Sorry, it's not a boolean. A tristate value. From the definition
> (Back, NoMove, Forward) = (-1, 0, 1), (dir1 == -dir2) if
> NoMovement did not exist. If it is not guranteed,
> 
> (dir1 != 0 && dir1 == -dir2) ?

Maybe just add ScanDirectionIsOpposite(dir1, dir2) with that
definition? :-)

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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  Cc: alvherre@2ndquadrant.com, horikyota.ntt@gmail.com, 9erthalion6@gmail.com, florisvannee@optiver.com, jesper.pedersen@redhat.com, david.rowley@2ndquadrant.com, thomas.munro@gmail.com, jtc331@gmail.com, rafia.pghackers@gmail.com, jeff.janes@gmail.com, pg@bowt.ie, tomas.vondra@2ndquadrant.com, thomas.munro@enterprisedb.com, bhushan.uparkar@gmail.com, a.korotkov@postgrespro.ru
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