Re: Parallel Plans and Cost of non-filter functions

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Paul Ramsey <pramsey(at)cleverelephant(dot)ca>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Parallel Plans and Cost of non-filter functions
Date: 2017-11-07 03:00:16
Message-ID: CAA4eK1JmGtnF7Q4O-V3Ya9-nPwXb=Opmcp0V74BXP9EW3nHBNA@mail.gmail.com
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On Mon, Nov 6, 2017 at 7:40 PM, Paul Ramsey <pramsey(at)cleverelephant(dot)ca> wrote:
> From my perspective, this is much much better. For sufficiently large
> tables, I get parallel behaviour without jimmying with the defaults on
> parallel_setup_cost and parallel_tuple_cost. *And*, the parallel behaviour
> *is* sensitive to the costs of functions in target lists, so reasonably
> chosen costs will flip us into a parallel mode for expensive functions
> against smaller tables too.
>

Thanks for the confirmation.

> Hopefully some variant of this finds it's way into core! Is there any way I
> can productively help?

You have already helped a lot by providing the use case, but feel free
to ping on that thread if you find it is not moving.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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