Excerpts from Narasimha Murthy-VRFX87's message of jue may 20 02:47:21 -0400 2010:
> Hi Alvaro Herrera,
>
> Since, my original plan was to run the auto-vacuum daily EXACTLY at 5 am, I wanted to know which seconds of a minute.
Myquery in other word was, if I set autovacuum_naptime to 1 hr, which minute of an hour the auto-vacuum runs (oth min,
15thmin or something else).
Yeah, you have no way to be know. I guess you could turn autovacuum off
in postgresql.conf all day, and exactly at 5am you have a cron job that
edits postgresql.conf and reloads Postgres. This would start up
autovacuum, which would then continue with the regular schedule.
This is hardly ideal; there were plans to improve on this by having an
autovacuum schedule, but I think the demand for this feature has
decreased considerable, so I haven't given it any minute's thought.
> From the clarification given by the you and other community members, I now understood that autovacuum is designed to
runfrequently in the background, not designed to run once a day at a specific time. Due to this design intent,
autovacuum_naptimeis set to 1 min by default and autovacuum runs lazy/plain/standard vacuum commands (so that Vacuum
canrun concurrently with other normal DB operations).
Correct.
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