Re: Parallel Inserts in CREATE TABLE AS

On Thu, May 27, 2021 at 1:03 PM tsunakawa.takay@fujitsu.com
<tsunakawa.takay@fujitsu.com> wrote:
>
> From: houzj.fnst@fujitsu.com <houzj.fnst@fujitsu.com>
> > Although, the 4 workers case still has performance degradation compared to
> > serial case.
> >
> > SERIAL: 58759.213 ms
> > PARALLEL 2 WORKER [NOT SKIP FSM]: 68390.221 ms  [SKIP FSM]:
> > 58633.924 ms
> > PARALLEL 4 WORKER [NOT SKIP FSM]: 67448.142 ms   [SKIP FSM]:
> > 66,960.305 ms
>
> Can you see any difference in table sizes?

Also, the number of pages the table occupies in each case along with
table size would give more insights.

I do as follows to get the number of pages a relation occupies:
CREATE EXTENSION pgstattuple;
SELECT pg_relpages('test');

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com