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. I will add this to the final CF for Postgres 14. Thanks -- Peter Geoghegan
v1-0001-Lower-vacuum_cost_page_miss-s-default-to-3.patch
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