Date: Sat, 3 Apr 2021 09:16:51 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: aditya desai <admad123@gmail.com>,
	pgsql-performance@lists.postgresql.org
Subject: Re: SELECT Query taking 200 ms on PostgreSQL compared to 4 ms on
 Oracle after migration.
Message-ID: <20210403141651.GI6592@telsasoft.com>
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On Sat, Apr 03, 2021 at 04:08:01PM +0200, Pavel Stehule wrote:
> so 3. 4. 2021 v 15:38 odesílatel aditya desai <admad123@gmail.com> napsal:
> > "Gather (cost=1000.43..1002.75 rows=1 width=127) (actual
> > time=174.318..198.539 rows=1 loops=1)"
> > " Workers Planned: 1"
> > " Workers Launched: 1"
> > " Single Copy: true"
> > " -> Index Scan using address1_i7 on address1 dom (cost=0.43..2.65 rows=1
> > width=127) (actual time=0.125..0.125 rows=1 loops=1)"
> > " Index Cond: (address_key = 6113763)"
> > "Planning Time: 0.221 ms"
> > "Execution Time: 198.601 ms"
> 
> You should have broken configuration - there is not any reason to start
> parallelism -  probably some option in postgresql.conf has very bad value.
> Second - it's crazy to see 200 ms just on interprocess communication -
> maybe your CPU is overutilized.

It seems like force_parallel_mode is set, which is for debugging and not for
"forcing things to go faster".  Maybe we should rename the parameter, like
parallel_mode_testing=on.

http://rhaas.blogspot.com/2018/06/using-forceparallelmode-correctly.html

-- 
Justin