Re: [HACKERS] [PATCH] Incremental sort

From: Antonin Houska <ah(at)cybertec(dot)at>
To: Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] [PATCH] Incremental sort
Date: 2017-11-22 10:22:30
Message-ID: 5513.1511346150@localhost
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Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> Antonin Houska <ah(at)cybertec(dot)at> wrote:

> > * ExecIncrementalSort()
> >
> > ** if (node->tuplesortstate == NULL)
> >
> > If both branches contain the expression
> >
> > node->groupsCount++;
> >
> > I suggest it to be moved outside the "if" construct.
> Done.

One more comment on this: I wonder if the field isn't incremented too
early. It seems to me that the value can end up non-zero if the input set is
to be empty (not sure if it can happen in practice).

And finally one question about regression tests: what's the purpose of the
changes in contrib/postgres_fdw/sql/postgres_fdw.sql ? I see no
IncrementalSort node in the output.

Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt

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