| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Fabrízio Mello <fabriziomello(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Seq Scan |
| Date: | 2015-01-11 21:57:05 |
| Message-ID: | CA+TgmoY2uksfjivmYwhBpBs=DPTJ0pk1b7A+gfLjoE-Vn8F_Ug@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sun, Jan 11, 2015 at 5:27 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> * Robert Haas (robertmhaas(at)gmail(dot)com) wrote:
>> On Thu, Jan 8, 2015 at 2:46 PM, Stephen Frost <sfrost(at)snowman(dot)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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