From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andy Fan <zhihui.fan1213@gmail.com>
cc: Robert Haas <robertmhaas@gmail.com>,
        Amit Langote <amitlangote09@gmail.com>,
        Justin Pryzby <pryzby@telsasoft.com>,
        "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: FailedAssertion("pd_idx == pinfo->nparts",
 File: "execPartition.c", Line: 1689)
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Comments: In-reply-to Andy Fan <zhihui.fan1213@gmail.com>
	message dated "Thu, 06 Aug 2020 21:52:23 +0800"
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Date: Thu, 06 Aug 2020 10:42:10 -0400
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Andy Fan <zhihui.fan1213@gmail.com> writes:
> On Thu, Aug 6, 2020 at 12:02 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> See my straw-man proposal downthread.

> Thanks for your explanation, I checked it again and it looks a very clean
> method.  The attached is a draft patch based on my understanding.  Hope
> I didn't  misunderstand you..

Ah, I was going to play arond with that today, but you beat me to it ;-)

A few thoughts after a quick look at the patch:

* I had envisioned that there's a custom GUC controlling the lock ID
used; this would allow blocking different sessions at different points,
if we ever need that.  Also, I'd make the GUC start out as zero which
means "do nothing", so that merely loading the module has no immediate
effect.

* Don't really see the point of the before-planning lock.

* Rather than exposing internal declarations from lockfuncs.c, you
could just write calls to pg_advisory_lock_int8 etc. using
DirectFunctionCall1.

* We need some better name than "test_module".  I had vaguely thought
about "delay_execution", but am surely open to better ideas.

			regards, tom lane