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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Rafia Sabih <rafia.sabih@enterprisedb.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: PostgreSQL Developers <pgsql-hackers@postgresql.org>
Subject: Re: [HACKERS] [POC] Faster processing at Gather node
Date: Wed, 15 Nov 2017 10:54:03 -0800
Message-ID: <20171115185403.xf476nhzpkgoddor@alap3.anarazel.de> (raw)
In-Reply-To: <CA+Tgmoa5azAJEQLHhCAfdyw+N7qJWTBm3DVGT7aqA94-r9Cmaw@mail.gmail.com>
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Hi,

On 2017-11-15 13:48:18 -0500, Robert Haas wrote:
> I think that we need a little bit deeper analysis here to draw any
> firm conclusions.

Indeed.


> I suspect that one factor is that many of the queries actually send
> very few rows through the Gather.

Yep. I kinda wonder if the same result would present if the benchmarks
were run with parallel_leader_participation. The theory being what were
seing is just that the leader doesn't accept any tuples, and the large
queue size just helps because workers can run for longer.


Greetings,

Andres Freund




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