On Tue, May 12, 2020 at 2:41 PM Bruce Momjian <br...@momjian.us> wrote:
> On Tue, May 12, 2020 at 05:40:14PM -0400, Bruce Momjian wrote: > > On Tue, May 12, 2020 at 10:26:27AM +0000, PG Doc comments form wrote: > > > The following documentation comment has been logged on the website: > > > > > > Page: > https://www.postgresql.org/docs/11/runtime-config-autovacuum.html > > > Description: > > > > > > The `autovacuum_vacuum_cost_delay` setting changes to 2ms in > PostgreSQL 12 > > > but in the old Postgresql version, the default setting is still 20ms. I > > > would suggest adding a suggestion in the old document > > > to lower the autovacuum_vacuum_cost_delay as: > > > > > > > The default value of autovacuum_vacuum_cost_delay is reduced to 2ms > in > > > PostgreSQL 12. Reducing the autovacuum_vacuum_cost_delay will make the > > > autovacuum more aggressive and might reduce the vacuum cost for > > > write-intensive workload on big table. > > > > Uh, we usually don't suggest new defaults in back branches. > > Basically, what I am saying is that if you want this, it would be a new > behavior that would need general discussion. > > The proposal is to document in versions 9.4 to 11 that the recommended value for the setting is 2ms while for reasons of continuity the default in these versions is 20ms. I don't really see any harm in it. Its not like the choice to reduce the value was made because of new features introduced in 12 - it was a re-evaluation of a 15 year old default. David J.
