On Thu, Jul 14, 2016 at 11:16 PM, Madusudanan.B.N <b.n.madusudanan@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 ?
