Date: Fri, 21 Sep 2018 10:43:47 -0700
From: Andres Freund <andres@anarazel.de>
To: Sergei Kornilov <sk@zsrv.org>
Cc: Robert Haas <robertmhaas@gmail.com>,
	Alvaro Herrera <alvherre@2ndquadrant.com>,
	Michael Paquier <michael@paquier.xyz>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: pgsql: Improve autovacuum logging for aggressive and
 anti-wraparound ru
Message-ID: <20180921174347.wvszsn7uk56zvz7o@alap3.anarazel.de>
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Hi,

On 2018-09-21 20:38:16 +0300, Sergei Kornilov wrote:
> > My first question was whether TWO of them were dead code ... isn't an
> > aggressive vacuum to prevent wraparound, and a vacuum to prevent
> > wraparound aggressive?
> Maybe i am wrong, aggressive autovacuum was your commit.
> Message split was in b55509332f50f998b6e8b3830a51c5b9d8f666aa
> Aggressive autovacuum was in fd31cd265138019dcccc9b5fe53043670898bc9f
> 
> If aggressive really is wraparound without difference - i think we need refactor this code, it is difficult have two different flags for same purpose.
> 
> But as far i can see it is possible have aggressive non-wraparound vacuum. One important difference - regular and aggressive regular can be canceled by backend,.wraparound autovacuum can not. (by checking PROC_VACUUM_FOR_WRAPAROUND in src/backend/storage/lmgr/proc.c )

Yes, without checking the code, they should be different. Aggressive is
controlled by vacuum_freeze_table_age whereas anti-wrap is controlled by
autovacuum_freeze_max_age (but also implies aggressive).

Greetings,

Andres Freund