From: Floris Van Nee <florisvannee@Optiver.com>
To: Dmitry Dolgov <9erthalion6@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>
CC: David Rowley <dgrowleyml@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>
Thread-Topic: Index Skip Scan [External]
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Date: Mon, 6 Apr 2020 18:31:08 +0000
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Subject: RE: Index Skip Scan
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>=20
> Hm, I wasn't aware about this one, thanks for bringing this up. Btw, Flor=
is, I
> would appreciate if in the future you can make it more visible that chang=
es you
> suggest contain some fixes. E.g. it wasn't clear for me from your previou=
s email
> that that's the case, and it doesn't make sense to pull into different di=
rection
> when we're trying to achieve the same goal :)

I wasn't aware that this particular case could be triggered before I saw Di=
lip's email, otherwise I'd have mentioned it here of course. It's just that=
 because my patch handles filter conditions in general, it works for this c=
ase too.

>=20
> > > In the patch I posted a week ago these cases are all handled
> > > correctly, as it introduces this extra logic in the Executor.
> >
> > Okay, So I think we can merge those fixes in Dmitry's patch set.
>=20
> I'll definitely take a look at suggested changes in filtering part.

It may be possible to just merge the filtering part into your patch, but I'=
m not entirely sure. Basically you have to pull the information about skipp=
ing one level up, out of the node, into the generic IndexNext code.=20

I'm eager to get some form of skip scans into master - any kind of patch th=
at makes this possible is fine by me. Long term I think my version provides=
 a more generic approach, with which we can optimize a much broader range o=
f queries. However, since many more eyes have seen your patch so far, I hop=
e yours can be committed much sooner. My knowledge on this committer proces=
s is limited though. That's why I've just posted mine so far in the hope of=
 collecting some feedback, also on how we should continue with the process.

-Floris