From: | Greg Nancarrow <gregn4422(at)gmail(dot)com> |
---|---|
To: | "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> |
Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, vignesh C <vignesh21(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)fujitsu(dot)com>, "Tang, Haiying" <tanghy(dot)fnst(at)cn(dot)fujitsu(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com> |
Subject: | Re: Parallel INSERT (INTO ... SELECT ...) |
Date: | 2021-02-08 08:04:27 |
Message-ID: | CAJcOf-fd51zqtCOGCWa7=Gjx8Lh9nAApY6Q0rUq9hAfY1M4Msg@mail.gmail.com |
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On Mon, Feb 8, 2021 at 6:00 PM Hou, Zhijie <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> wrote:
>
> > Posting an updated set of patches.
>
> A minor comment about doc.
>
> + <para>
> + Where the above target table features are determined to be, at worst,
> + parallel-restricted, rather than parallel-unsafe, at least a parallel table
> + scan may be used in the query plan for the <literal>INSERT</literal>
> + statement. For more information about Parallel Safety, see
> + <xref linkend="parallel-safety"/>.
> + </para>
>
> It seems does not mention that if target table is a foreign/temp table, a parallel table scan may be used.
>
> So how about:
>
> + <para>
> + Where the target table is a foreign/temporary table or the above target table features
> + are determined to be, at worst, parallel-restricted, rather than parallel-unsafe,
> + at least a parallel table scan may be used in the query plan for the
> + <literal>INSERT</literal> statement. For more information about Parallel Safety,
> + see <xref linkend="parallel-safety"/>.
> + </para>
>
Thanks. You're right, I should probably update the docs to clarify
those two cases.
(I had removed them from the list of parallel-unsafe things, but not
pointed out that a parallel table scan could still be used in these
cases).
Regards,
Greg Nancarrow
Fujitsu Australia
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