Re: Parallel Seq Scan - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Parallel Seq Scan
Date
Msg-id CA+TgmoY2uksfjivmYwhBpBs=DPTJ0pk1b7A+gfLjoE-Vn8F_Ug@mail.gmail.com
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In response to Re: Parallel Seq Scan  (Stephen Frost <sfrost@snowman.net>)
Responses Re: Parallel Seq Scan
Re: Parallel Seq Scan
List pgsql-hackers
On Sun, Jan 11, 2015 at 5:27 AM, Stephen Frost <sfrost@snowman.net> wrote:
> * Robert Haas (robertmhaas@gmail.com) wrote:
>> On Thu, Jan 8, 2015 at 2:46 PM, Stephen Frost <sfrost@snowman.net> wrote:
>> > Yeah, if we come up with a plan for X workers and end up not being able
>> > to spawn that many then I could see that being worth a warning or notice
>> > or something.  Not sure what EXPLAIN has to do anything with it..
>>
>> That seems mighty odd to me.  If there are 8 background worker
>> processes available, and you allow each session to use at most 4, then
>> when there are >2 sessions trying to do parallelism at the same time,
>> they might not all get their workers.  Emitting a notice for that
>> seems like it would be awfully chatty.
>
> Yeah, agreed, it could get quite noisy.  Did you have another thought
> for how to address the concern raised?  Specifically, that you might not
> get as many workers as you thought you would?

I'm not sure why that's a condition in need of special reporting.

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



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