On Fri, 2020-03-27 at 10:18 +1300, David Rowley wrote: > > > I believe there are enough options to disable insert-only vacuuming for > > > an individual table: > > > > > - Set the threshold to 2147483647. True, that will not work for very > > > large tables, but I think that there are few tables that insert that > > > many rows before they hit autovacuum_freeze_max_age anyway. > > > > > > - Set the scale factor to some astronomical value. > > > > Meh. You *are* adding new semantics with these. And they're terrible. > > I've modified this to allow a proper way to disable the entire feature > by allowing the setting to be set to -1 to disable the feature. I feel > people are fairly used to using -1 to disable various features (e.g. > log_autovacuum_min_duration). I've used the special value of -2 for > the reloption to have that cascade to using the GUC instead. The > autovacuum_vacuum_insert_threshold reloption may be explicitly set to > -1 to disable autovacuums for inserts for the relation. > > I've also knocked the default threshold down to 1000. I feel this is a > better value given that the scale factor is now 0.2. There seemed to > be no need to exclude smaller tables from seeing gains such as > index-only scans. > > If nobody objects, I plan to push this one shortly.
Thanks for the help! The new meaning of -2 should be documented, other than that it looks good to me. I'll accept the new semantics, but they don't make me happy. People are used to -1 meaning "use the GUC value instead". I still don't see why we need that. Contrary to Andres' opinion, I don't think that disabling a parameter by setting it to a value high enough that it does not take effect is a bad thing. I won't put up a fight though. Yours, Laurenz Albe
