Re: Choosing parallel_degree

On 17/03/2016 02:07, James Sewell wrote:
>
> On Thu, Mar 17, 2016 at 5:05 AM, Julien Rouhaud
> <julien(dot)rouhaud(at)dalibo(dot)com <mailto:julien(dot)rouhaud(at)dalibo(dot)com>> wrote:
>
>
> attached v3 drops the GUC part.
>
>
> This looks good good. I do think that some threshold control would be
> good in the long term - but you are right Robert it just feels strange.
>
> Maybe once the final formula is implemented in 9.7+ and this gets some
> real world use cases it can be revisited?
>
> One thing I really, really like about the way the new patch works is
> that you can set parallel_degree on an inheritance parent, then that
> will set the minimum workers for all associated children (when accessing
> from the parent).
>
> Currently this patch will not fire on small tables even
> when parallel_degree is set, can we fix this by adding a check
> for ref->parallel_degree to the table size condition?
>

Actually, a parallel plan will be created, since in this case the
rel->reloptkind will be RELOPT_OTHER_MEMBER_REL, not RELOPT_BASEREL.

--
Julien Rouhaud
http://dalibo.com - http://dalibo.org