Re: [sqlsmith] Parallel worker crash on seqscan

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andreas Seltenreich <seltenreich(at)gmx(dot)de>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [sqlsmith] Parallel worker crash on seqscan
Date: 2016-11-21 17:14:21
Message-ID: CA+TgmoYQTTa8=7zu1er-2+sQS4jYa9JYVb=89UmvQUc6t4oReg@mail.gmail.com
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On Mon, Nov 21, 2016 at 12:00 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Mon, Nov 21, 2016 at 11:43 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> so what we've got is a case where a parameter computed by the FunctionScan
>>> (in the master) would need to be passed into the parallel workers at
>>> runtime. Do we have code for that at all? If so where is it?
>
>> No, that's not supposed to happen.
>
> OK, that makes this a planner failure: we should not have allowed this
> query to become parallelized.
>
>> Maybe it's checking the quals but not recursing into the tlist?
>
> It seems like maybe searching for individual Params is the wrong thing.
> Why are we allowing it to generate a parameterized Gather path at all?
> Given the lack of any way to transmit runtime param values to the worker,
> I can't see how that would ever work.

Hmm, so you're thinking it could be the job of generate_gather_paths()
to make sure we don't do that?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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