Ah I see... I thought that by running the vacuum more often, its cost would be divided in a more or less linear fashion, with a base constant cost. While I read about the vacuum process, I did not check the source code or even read about the actual algorithm, so I am sorry for having asked a nonsensical question :)
It was theoretical, my current database does what you suggest, but I might increase workers as about 10 tables see a heavy update rate and are quite large compared to the others. Sébastien On Fri, Sep 14, 2012 at 5:49 PM, Josh Berkus <j...@agliodbs.com> wrote: > > > I am pondering about this... My thinking is that since *_scale_factor > need > > to be set manually for largish tables (>1M), why not > > set autovacuum_vacuum_scale_factor and autovacuum_analyze_scale_factor, > and > > increase the value of autovacuum_vacuum_threshold to, say, 10000, and > > autovacuum_analyze_threshold > > to 2500 ? What do you think ? > > I really doubt you want to be vacuuming a large table every 10,000 rows. > Or analyzing every 2500 rows, for that matter. These things aren't > free, or we'd just do them constantly. > > Manipulating the analyze thresholds for a large table make sense; on > tables of over 10m rows, I often lower autovacuum_analyze_scale_factor > to 0.02 or 0.01, to get them analyzed a bit more often. But vacuuming > them more often makes no sense. > > > Also, with systems handling 8k-10k tps and dedicated to a single > database, > > would there be any cons to decreasing autovacuum_naptime to say 15s, so > > that the system perf is less spiky ? > > You might also want to consider more autovacuum workers. Although if > you've set the thresholds as above, that's the reason autovacuum is > always busy and not keeping up ... > > -- > Josh Berkus > PostgreSQL Experts Inc. > http://pgexperts.com > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
