Re: Rename max_parallel_degree?
Josh Berkus <josh@agliodbs.com>
From: Josh berkus <josh@agliodbs.com>
To: Peter Geoghegan <pg@heroku.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>,
Noah Misch <noah@leadboat.com>, David Rowley <david.rowley@2ndquadrant.com>,
Amit Kapila <amit.kapila16@gmail.com>,
Alvaro Herrera <alvherre@2ndquadrant.com>,
Magnus Hagander <magnus@hagander.net>, Bruce Momjian <bruce@momjian.us>,
PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-05-31T17:23:13Z
Lists: pgsql-hackers
On 05/31/2016 10:16 AM, Peter Geoghegan wrote: > On Tue, May 31, 2016 at 10:10 AM, Josh berkus <josh@agliodbs.com> wrote: >> "max_parallel_degree is the amount of parallelism in the query, with the >> understanding that the original parent process counts as 1, which means >> that if you set it to 1 you get no parallelism, and if you want 4 >> parallel workers you need to set it to 5." >> >> Which one of those is going to require more explanations on -general and >> -novice? Bets? >> >> Let's not be complicated for the sake of being complicated. > > But the distinction between parallel workers and backends that can > participate in parallel query does need to be user-visible. Worker > processes are a commodity (i.e. the user must consider > max_worker_processes). It's still WAY simpler to understand "max_parallel is the number of parallel workers I requested". Any system where you set it to 2 and get only 1 worker on an idle system is going to cause endless queries on the mailing lists. -- -- Josh Berkus Red Hat OSAS (any opinions are my own)