On Mon, Mar 7, 2016 at 11:52 AM, Peter Geoghegan <p...@heroku.com> wrote: > > On Sun, Mar 6, 2016 at 9:59 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Perhaps it was intentional when written, but if Robert's advice is correct > > that the new upper-planner path nodes should copy up parallel_degree from > > their children, then it cannot be the case that parallel_degree>0 in a > > node above the scan level implies that that node type has any special > > behavior for parallelism. > >
Right. > > > I continue to bemoan the lack of documentation about what these fields > > mean. > > Point taken and if Robert doesn't feel otherwise, I can try to write a patch to explain the newly added fields. > > As far as I can find, the sum total of the documentation about > > this field is > > > > int parallel_degree; /* desired parallel degree; 0 = not parallel */ > > While it doesn't particularly relate to parallel joins, I've expressed > a general concern about the max_parallel_degree GUC that I think is > worth considering again: > > http://www.postgresql.org/message-id/cam3swzrs1mtvrkkasy1xbshgzxkd6-hnxx3gq7x-p-dz0zt...@mail.gmail.com > > In summary, I think it's surprising that a max_parallel_degree of 1 > doesn't disable parallel workers entirely. > I have responded on the thread where you have raised that point with my thoughts, discussing it here on a separate point can dilute the purpose of this thread. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
