Re: Parallel Seq Scan

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Noah Misch <noah(at)leadboat(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>, Jeff Davis <pgsql(at)j-davis(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Fabrízio Mello <fabriziomello(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Parallel Seq Scan
Date: 2015-10-23 04:31:29
Message-ID: 55910.1445574689@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Thu, Oct 15, 2015 at 8:23 PM, Noah Misch <noah(at)leadboat(dot)com> wrote:
>>> Would it work to define this as "if non-NULL,
>>> params lacking a 1-bit may be safely ignored"? Or some other tweak
>>> that basically says that you don't need to care about this, but you
>>> can if you want to.

>> ... this is a better specification.

> Here's an attempt to implement that.

BTW, my Salesforce colleagues have been bit^H^H^Hgriping for quite some
time about the performance costs associated with translating between
plpgsql's internal PLpgSQL_datum-array format and the ParamListInfo
representation. Maybe it's time to think about some wholesale redesign of
ParamListInfo? Because TBH this patch doesn't seem like much but a kluge.
It's mostly layering still-another bunch of ad-hoc restrictions on
copyParamList, without removing any one of the kluges we had already.

regards, tom lane

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