Date: Sat, 12 Oct 2024 19:30:58 +0200
From: Marc SCHAEFER <alphanet-postgresql-general@alphanet.ch>
To: pgsql-general@lists.postgresql.org
Subject: Naive question about multithreading/multicore
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Hello,

on a machine where starting two processes:
   perl -e 'while (1) { ; }'
I see two processed at 100% CPU, which is expected (with top).

Now, if I do:

template1=> SELECT COUNT(*) FROM pg_class a, pg_class b, pg_class c;

I see only one 100% CPU PostgreSQL process.

I read that while PostgreSQL connetions lead to a UNIX process model,
which is better for isolation, some operations have been parallelized
and can use more than one core/thread.

Maybe this specific case was not (yet?) parallelized, or should it
be and thus something is issing in my configuration?

Thank you.

PS: psql (13.16 (Debian 13.16-0+deb11u1))