On Tue, Mar 2, 2021 at 10:07 PM David Rowley <dgrowle...@gmail.com> wrote: > > On Wed, 3 Mar 2021 at 01:12, Magnus Hagander <mag...@hagander.net> wrote: > > > > On Tue, Mar 2, 2021 at 7:52 AM David Rowley <dgrowle...@gmail.com> wrote: > > > I have seen it happen that an instance has a vacuum_cost_limit set and > > > someone did start the database in single-user mode, per the advice of > > > the error message only to find that the VACUUM took a very long time > > > due to the restrictive cost limit. I struggle to imagine why anyone > > > wouldn't want the vacuum to run as quickly as possible in that > > > situation. > > > > Multiple instances running on the same hardware and only one of them > > being in trouble? > > You might be right. I'm not saying it's a great idea but thought it > was worth considering. > > We could turn to POLA and ask; what would you be more surprised at; 1) > Your database suddenly using more I/O than it had been previously, or; > 2) Your database no longer accepting DML.
I think we misunderstand each other. I meant this only as a comment about the idea of ignoring the cost limit in single user mode -- that is, it's a reason to *want* vacuum to not run as quickly as possible in single user mode. I should've trimmed the email better. I agree with your other idea, that of kicking in a more aggressive autovacuum if it's not dealing with things fast enough. Maybe even on an incremental way - that is run with the default, then at another threshold drop them to half, and at yet another threshold drop them to 0. I agree that pretty much anything is better than forcing the user into single user mode. -- Magnus Hagander Me: https://www.hagander.net/ Work: https://www.redpill-linpro.com/
