Re: Parallel Apply

Álvaro Herrera <alvherre@kurilemu.de>

From: Álvaro Herrera <alvherre@kurilemu.de>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, 'Amit Kapila' <amit.kapila16@gmail.com>, Tomas Vondra <tomas@vondra.me>, Dilip Kumar <dilipbalaut@gmail.com>, Andrei Lepikhov <lepihov@gmail.com>, wenhui qiu <qiuwenhuifx@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-04-17T05:48:12Z
Lists: pgsql-hackers
Hello,

I have a quick question about this work -- is there an expectation of
how quicker parallel apply is, compared to our normal (serial) apply,
for average cases?  Are we talking 20% faster, 2x faster, 10x faster?

(When I say average, I mean not considering fringe cases where the
workload is such that very little paralelization can be done, and also
those where you have a contrived case with one thousand parallel
processes each making progress separately to the point where you get
ridiculously high numbers.  I mean something that can occur in realistic
workloads.)

My point is that if it's 20% faster, it's nice.  But if it's, say, 4x
faster, then it's probably groundbreaking to the point that it may
enable new use cases not currently possible.

Thoughts, pointers?

Many thanks

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"¿Qué importan los años?  Lo que realmente importa es comprobar que
a fin de cuentas la mejor edad de la vida es estar vivo"  (Mafalda)