| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Frédéric Yhuel <frederic(dot)yhuel(at)dalibo(dot)com> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Allow parallel plan for referential integrity checks? |
| Date: | 2022-02-14 14:33:50 |
| Message-ID: | CA+TgmobLe8hTPJJ5fnLn+Hw0YnUGRr85ROD5M2zrkVKhBCPkyA@mail.gmail.com |
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On Mon, Feb 7, 2022 at 5:26 AM Frédéric Yhuel <frederic(dot)yhuel(at)dalibo(dot)com> wrote:
> I noticed that referential integrity checks aren't currently
> parallelized. Is it on purpose?
It's not 100% clear to me that it is safe. But on the other hand, it's
also not 100% clear to me that it is unsafe.
Generally, I only added CURSOR_OPT_PARALLEL_OK in places where I was
confident that nothing bad would happen, and this wasn't one of those
places. It's something of a nested-query environment -- your criterion
#6. How do we know that the surrounding query isn't already parallel?
Perhaps because it must be DML, but I think it must be more important
to support parallel DML than to support this.
I'm not sure what the right thing to do here is, but I think it would
be good if your patch included a test case.
--
Robert Haas
EDB: http://www.enterprisedb.com
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