| From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] why not parallel seq scan for slow functions |
| Date: | 2017-11-29 05:01:26 |
| Message-ID: | CAB7nPqSw6CNQMiN0ohiqck7syGnJpz61bk-=nbFf71mCdpwyDA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Nov 10, 2017 at 4:42 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Nov 9, 2017 at 3:47 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> I think I understood your concern after some offlist discussion and it
>> is primarily due to the inheritance related check which can skip the
>> generation of gather paths when it shouldn't. So what might fit
>> better here is a straight check on the number of base rels such that
>> allow generating gather path in set_rel_pathlist, if there are
>> multiple baserels involved. I have used all_baserels which I think
>> will work better for this purpose.
>
> Yes, that looks a lot more likely to be correct.
>
> Let's see what Tom thinks.
Moved to next CF for extra reviews.
--
Michael
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