Re: Cost model for parallel CREATE INDEX

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Cost model for parallel CREATE INDEX
Date: 2017-03-04 08:47:13
Message-ID: CAH2-WzkqpZfpaE3Yx4AAztYypOdONWmTs=SsF2K8KupoagptaQ@mail.gmail.com
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On Sat, Mar 4, 2017 at 12:43 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Oh. But then I don't see why you need min_parallel_anything. That's
> just based on an estimate of the amount of data per worker vs.
> maintenance_work_mem, isn't it?

Yes -- and it's generally a pretty good estimate.

I don't really know what minimum amount of memory to insist workers
have, which is why I provisionally chose one of those GUCs as the
threshold.

Any better ideas?

--
Peter Geoghegan

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