Re: Setting autovacuum_vacuum_scale_factor to 0 a good idea ?

> 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