Re: Choosing parallel_degree

On 04/11/2016 08:57 PM, Julien Rouhaud wrote:
>> >Expected = Expecting worker8 information , also loops=10 (including the
>> >Master)
>> >
> Even if you set a per-table parallel_degree higher than
> max_parallel_degree, it'll be maxed at max_parallel_degree.
>
> Then, the explain shows that the planner assumed it'll launch 9 workers,
> but only 8 were available (or needed perhaps) at runtime.
>
Right, if we increase max_worker_processes value in postgresql.conf file 
then
we are able to see the worker information in explain plan.

if parallel_degree value is higher than max_parallel_degree i.e

parallel_degree = 20,  max_parallel_degree=10  => [ select query 
accepting 10 workers ]

but in general  where table doesn't have parallel_degree set and 
max_parallel_degree is
set to 10 then select query is showing only 2 workers .

-- 
regards,tushar