Re: Choosing parallel_degree
| От | Simon Riggs |
|---|---|
| Тема | Re: Choosing parallel_degree |
| Дата | |
| Msg-id | CANP8+jLJMXw4amnNRmQdZC9i7r6+3xZiPmUf3iB0x4CBcfKNPA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Choosing parallel_degree (Amit Kapila <amit.kapila16@gmail.com>) |
| Список | pgsql-hackers |
On 12 April 2016 at 07:58, Amit Kapila <amit.kapila16@gmail.com> wrote:
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On Tue, Apr 12, 2016 at 3:15 AM, Simon Riggs <simon@2ndquadrant.com> wrote:On 8 April 2016 at 17:49, Robert Haas <robertmhaas@gmail.com> wrote:With the patch, you can - if you wish - substitute
some other number for the one the planner comes up with.I saw you're using AccessExclusiveLock, the reason being it affects SELECTs.That is supposed to apply when things might change the answer from a SELECT, whereas this affects only the default for a plan.By this theory, shouldn't any other parameter like n_distinct_inherited which just effects the plan required lower lock level?
It should, yes, and I'm as surprised to see it isn't as you are.
Thread: Fabrizio was asked by Robert to provide or document an analysis of why each setting was OK to change; 9 days later he had not done so or replied, so I committed a reduced version of the patch that matched existing tests and code comments.
I guess we could have salvaged some more from it, but we didn't and there's never enough time.
If RMT allows, that can be changed or it can wait.
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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