Horton

Re: pgsql: Improve autovacuum logging for aggressive and anti-wraparound ru

Sergei Kornilov <sk@zsrv.org>

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From: Sergei Kornilov <sk@zsrv.org>
To: Robert Haas <robertmhaas@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-09-21T17:38:16Z
Lists: pgsql-hackers 
Hello, Robert

> 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 )

regards, Sergei

Commits

  1. Skip redundant anti-wraparound vacuums

  2. Improve autovacuum logging for aggressive and anti-wraparound runs

  3. In relevant log messages, indicate whether vacuums are aggressive.

  4. Don't vacuum all-frozen pages.