On 2018-Sep-27, PG Doc comments form wrote: > Page: https://www.postgresql.org/docs/10/static/runtime-config-autovacuum.html > > This page lists the different autovacuum options. Describing > autovacuum_vacuum_threshold and autovacuum_vacuum_scale_factor independently > adds confusion unless you are also reading > https://www.postgresql.org/docs/10/static/routine-vacuuming.html#AUTOVACUUM > where we have a formula for the threshold and scale factor.
True. > I suggest adding a reference for each one of the two parameters with a link > to the "Routine Vacuuming" section. I suggest adding "This number is added to the number coming from the autovacuum_vacuum_scale_factor parameter for each table" just before the "This parameter can only be set" phrase. So we'd end up with this: autovacuum_vacuum_threshold (integer) Specifies the minimum number of updated or deleted tuples needed to trigger a VACUUM in any one table. The default is 50 tuples. This number is added to the number coming from the autovacuum_vacuum_scale_factor parameter for each table. This parameter can only be set in the postgresql.conf file or on the server command line; but the setting can be overridden for individual tables by changing table storage parameters. autovacuum_vacuum_scale_factor (floating point) Specifies a fraction of the table size to add to autovacuum_vacuum_threshold when deciding whether to trigger a VACUUM. The default is 0.2 (20% of table size). This number is added to the autovacuum_vacuum_threshold parameter for each table. This parameter can only be set in the postgresql.conf file or on the server command line; but the setting can be overridden for individual tables by changing table storage parameters. Same for the analyze parameters. I suppose we don't need any updates to the section of https://www.postgresql.org/docs/10/static/sql-createtable.html that explains the equivalent reloptions, since those ones are very succint anyway. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services