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
differentflags for same purpose.
>
> But as far i can see it is possible have aggressive non-wraparound vacuum. One important difference - regular and
aggressiveregular 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