From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Jeff Davis <pgsql@j-davis.com>
Cc: David Rowley <dgrowleyml@gmail.com>
Cc: Stephen Frost <sfrost@snowman.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: Melanie Plageman <melanieplageman@gmail.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: Default setting for enable_hashagg_disk
Date: Mon, 27 Jul 2020 15:52:32 -0400
Message-ID: <20200727195232.GA22546@alvherre.pgsql> (raw)
In-Reply-To: <CAH2-Wznmr5r2GtRh4h7AYP+d6EGyKFmKg39wp71ei2UC5db3zA@mail.gmail.com>
On 2020-Jul-27, Peter Geoghegan wrote:
> The v4-0001-Remove-hashagg_avoid_disk_plan-GUC.patch changes are
> surprisingly complicated. It would be nice if you could take a look at
> that aspect (or confirm that it's included in your review).
I think you mean "it replaces surprisingly complicated code with
straightforward code". Right? Because in the previous code, there was
a lot of effort going into deciding whether the path needed to be
generated; the new code just generates the path always.
Similarly the code to decide allow_hash in create_distinct_path, which
used to be nontrivial, could (if you wanted) be simplified down to a
single boolean condition. Previously, it was nontrivial only because
it needed to consider memory usage -- not anymore.
But maybe you're talking about something more subtle that I'm just too
blind to see.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, pg@bowt.ie, pgsql@j-davis.com, dgrowleyml@gmail.com, sfrost@snowman.net, tgl@sss.pgh.pa.us, andres@anarazel.de, bruce@momjian.us, robertmhaas@gmail.com, pryzby@telsasoft.com, melanieplageman@gmail.com, tomas.vondra@2ndquadrant.com
Subject: Re: Default setting for enable_hashagg_disk
In-Reply-To: <20200727195232.GA22546@alvherre.pgsql>
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