Re: Actuall row count of Parallel Seq Scan in EXPLAIN ANALYZE .

On Mon, Jun 20, 2016 at 12:47 PM, Amit Langote <
Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>
> On 2016/06/20 15:42, Amit Kapila wrote:
> >
> >>
> >> After spent time to investigate this behaviour, ISTM that the problem
> >> is nloops of Parallel Seq Scan.
> >> Parallel Seq Scan is done only once, but nloops is incremented to 3.
> >>
> >
> > nloops here indicates, that it is done for 2 workers and a master
backend.
>
> Does the way parallel instrumentation info is currently handled allow to
> also show the leader's info maybe like below:
>
> -> Parallel Seq Scan on public.pgbench_accounts
> (cost=0.00..205601.67 rows=4166667 width=0) (actual
> time=0.042..1685.542 rows=3333333 loops=3)
> Leader: actual time=x.xxx..xxxx.xxx rows=2800963 loops=1
> Worker 0: actual time=0.033..1657.486 rows=3457968 loops=1
> Worker 1: actual time=0.039..1702.979 rows=3741069 loops=1
>

Currently, we don't have a way to display information like above, however
feel free to propose a patch, if you find a neat way to achieve it.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com