On Thu, Jan 14, 2021 at 1:24 AM Peter Geoghegan <p...@bowt.ie> wrote: > > On Wed, Jan 6, 2021 at 7:43 PM Peter Geoghegan <p...@bowt.ie> wrote: > > More concretely, we could perhaps lower vacuum_cost_page_miss to 5. It > > has had the value as 10 as its default since 2004 (just like > > vacuum_cost_page_dirty, whose default has also not been changed since > > the start). These defaults were decided in a time when nbtree VACUUM > > could do lots of random I/O, there was no visibility map, etc. So this > > refresh is not just about hardware. > > Attached patch lowers vacuum_cost_page_miss to 3. I think that this > change in the default is both likely to be helpful in medium to large > installations, and unlikely to cause harm in small installations. If > I/O for reads made by VACUUM is naturally very slow (even in the > common case where it's entirely sequential), then that will naturally > provide additional throttling.
+1 for this in principle. Do you have any actual metrics between specifically choosing the value 3? Or is that off a gut feeling? -- Magnus Hagander Me: https://www.hagander.net/ Work: https://www.redpill-linpro.com/
