Re: why not parallel seq scan for slow functions

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: why not parallel seq scan for slow functions
Date: 2017-11-05 04:57:56
Message-ID: CAA4eK1+1H5Urm0_Wp-n5XszdLX1YXBqS_zW0f-vvWKwdh3eCJA@mail.gmail.com
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On Thu, Sep 21, 2017 at 2:35 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Tue, Sep 19, 2017 at 9:15 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
> wrote:
>>
>> On Wed, Sep 20, 2017 at 3:05 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
>> > On Tue, Sep 19, 2017 at 1:17 PM, Thomas Munro
>> > <thomas(dot)munro(at)enterprisedb(dot)com> wrote:
>> >>
>> >> On Thu, Sep 14, 2017 at 3:19 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
>> >> wrote:
>> >> > The attached patch fixes both the review comments as discussed above.
>> >
>> >
>> > that should be fixed by turning costs on the explain, as is the
>> > tradition.
>> >
>>
>> Right. BTW, did you get a chance to run the original test (for which
>> you have reported the problem) with this patch?
>
>
> Yes, this patch makes it use a parallel scan, with great improvement.
>

Thanks for the confirmation. Find rebased patch attached.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
parallel_paths_include_tlist_cost_v5.patch application/octet-stream 11.3 KB

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