On Tue, May 31, 2016 at 10:02 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> Now, this case is a little trickier. If we called it simply >> parallel_degree rather than max_parallel_degree, then it would have >> the same name as the reloption. But the reloption sets an exact >> value, and the GUC sets a cap, which is a significant difference. > > The reloption does not set an exact value, according to the code: > > /* > * Use the table parallel_degree, but don't go further than > * max_parallel_degree. > */ > parallel_degree = Min(rel->rel_parallel_degree, max_parallel_degree); > > although the existing documentation for it is so vague that you > couldn't tell from that.
True, max_parallel_degree is an overriding limit. But the point is that, without the reloption, you can't get lots of workers on a small table. The reloption lets you do that. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers