Re: WIP: [[Parallel] Shared] Hash

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Oleg Golovanov <rentech(at)mail(dot)ru>
Cc: Peter Geoghegan <pg(at)bowt(dot)ie>, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>
Subject: Re: WIP: [[Parallel] Shared] Hash
Date: 2017-04-26 23:03:48
Message-ID: CAEepm=19cRLMgSGH5zy-z=XHy2XmVYnTh9brSB+tvHaLB_8h5g@mail.gmail.com
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On Thu, Apr 27, 2017 at 5:13 AM, Oleg Golovanov <rentech(at)mail(dot)ru> wrote:
> Can you actualize your patch set? The error got from
> 0010-hj-parallel-v12.patch.

I really should get around to setting up a cron job to tell me about
that. Here's a rebased version.

The things currently on my list for this patch are:

1. Implement the skew optimisation.
2. Consider Andres's suggestion of splitting MultiExecHash into two
functions, serial and parallel version, rather than having all those
conditional blocks in there.
3. Figure out whether the shared BufFile stuff I propose would work
well for Peter Geoghegan's parallel tuple sort patch, by trying it
(I've made a start, more soon).
4. Figure out how the costing model needs to be tweaked, probably
based on experimentation.

I'm taking a short break to work on other things right now but will
post a version with those changes soon.

--
Thomas Munro
http://www.enterprisedb.com

Attachment Content-Type Size
parallel-shared-hash-v13.tgz application/x-gzip 63.2 KB

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