[hu3]

Does it affect performance? I might not want VACUUM to trigger during high workload.

[hans_castorp]

Yes it does, it makes things faster ;)

A common misconception about (auto) vacuum is, that you need to turn it off, to avoid performance problems.

The truth is: you need to make it more aggressive (= run it more frequently) if you have problems with the (additional) I/O load it generates.

[hu3]

Obviously I meant to ask if performance is affected during VACUUM.

@pg-gadfly's link answered it for me:

> VACUUM creates a substantial amount of I/O traffic, which can cause poor performance for other active sessions.

[pg-gadfly]

Since a vacuum operation uses processor cycles, it's impossible to say no.

Their wiki is pretty amazing source for postgres's operation: https://www.postgresql.org/docs/12/routine-vacuuming.html