From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
cc: Amit Kapila <amit.kapila16@gmail.com>, Noah Misch <noah@leadboat.com>,
        "Adam,
    Etienne (Nokia-TECH/Issy Les Moulineaux)" <etienne.adam@nokia.com>,
        PostgreSQL Bugs <pgsql-bugs@postgresql.org>,
        "Duquesne,
    Pierre (Nokia-TECH/Issy Les Moulineaux)" <pierre.duquesne@nokia.com>,
        pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: [BUGS] [postgresql 10 beta3] unrecognized node type: 90
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Comments: In-reply-to Robert Haas <robertmhaas@gmail.com>
	message dated "Mon, 28 Aug 2017 20:59:45 -0400"
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Date: Mon, 28 Aug 2017 22:17:20 -0400
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Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Aug 28, 2017 at 6:35 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Maybe parallel_aware should have more than two values, depending
>> on whether the result of the node is context-dependent or not.

> It seems likely the whole concept of parallel_aware is only only a
> zero-order approximation to what we really want.

Yeah, I agree --- but it's also clear that we don't yet know what it
should be.  We'll have to work that out as we accrete more functionality.

In the meantime, I think what we should do is commit the bug fix more or
less as I have it, and then work on Amit's concern about losing parallel
efficiency by separating the resetting of shared parallel-scan state
into a new plan tree traversal that's done before launching new worker
processes.  The only real alternative is to lobotomize the existing rescan
optimizations, and that seems like a really poor choice from here.

			regards, tom lane


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