On Thu, 2021-01-07 at 10:56 -0600, Henry Francisco Garcia Cortez wrote: > El mié, 6 ene 2021 a las 19:53, Laurenz Albe (<laurenz.albe@xxxxxxxxxxx>) escribió: > > > On Wed, 2021-01-06 at 11:05 -0600, Henry Francisco Garcia Cortez wrote: > > > I have a question why settings default postgresql has autovacuum_vacuum_scale_factor in 0.2 > > > is higher than autovacuum_analyze_scale_factor 0.1, so If want to tune these parameters, > > > I always must leave autovacuum_vacuum_scale_factor higher than autovacuum_analyze_scale_factor, > > > for instance I wanted to leave autovacuum_vacuum_scale_factor in 0.002 and > > > autovacuum_analyze_scale_factor in 0.001 > > > > The autovacuum scale factor has been twice the autoanalyze scale factor since the > > beginning. You could search the archives from around 2004 for a reason, but I'd > > say it might have to do with the fact that ANALYZE is much cheaper than VACUUM, > > and that the impact of bad statistics is usually more severe than the impact of > > some dead tuples. > > > > But there is no need for you to keep it that way when you change the parameters. > > For example, if you want to speed up index only scans, you may want to set > > "autovacuum_vacuum_scale_factor" to something like 0.01, but leave > > "autovacuum_analyze_scale_factor" at the default value. > > > > The values that you suggest seem much too low - that will result in autovacuum > > running all the time. > > Thanks for the information Laurenz Albe I have another question what will be effect > if there are autovacuums running all the time, what will be settings you could suggest me for > autovacuum_vacuum_scale_factor and autovacuum_analyze_scale_factor Unless there are indications to choose different values, stick with the default values of 0.1 and 0.2. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com
