On Thu, Jul 14, 2016 at 7:09 PM, Haribabu Kommi <kommi.harib...@gmail.com> wrote:
> On Thu, Jul 14, 2016 at 11:16 PM, Madusudanan.B.N > <b.n.madusuda...@gmail.com> wrote: > > > > 3) Is there any kind of toggle to enable parallel aggregate/join feature > ? > > > > I am able to generate parallel plan, The parallel plan may be costly > in your query compared > to other scans, because of which it is not selecting the parallel plan. > > It is possible that if the table size is very small or you are > selecting all records of the table > and etc. > > postgres=# insert into test values(generate_series(1,1000000), 'Test'); > INSERT 0 1000000 > postgres=# explain select * from test where f1 < 9900; > QUERY PLAN > > ----------------------------------------------------------------------------- > Gather (cost=1000.00..23719.93 rows=188964 width=105) > Workers Planned: 2 > -> Parallel Seq Scan on test (cost=0.00..22719.93 rows=78735 > width=105) > Filter: (f1 < 9900) > (4 rows) > For the above example, I can see that it does choose parallel plan. However as said above, for other cases it does not choose a parallel plan. Is there any other considerations apart from the mentioned ones on why pg would not choose a parallel plan ? > > > Regards, > Hari Babu > Fujitsu Australia > -- Regards, Madusudanan.B.N <http://madusudanan.com>
