Re: autovacuum on a -mostly- r/o table

[Edoardo Ceccarelli <eddy@xxxxxx>]

Bill Moran wrote:

In response to Edoardo Ceccarelli <eddy@xxxxxx>:

I have read that autovacuum cannot check to see pg load before launching 
vacuum but is there any patch about it? that would sort out the problem 
in a good and simple way.
Otherwise, which kind of set of parameters I should put in autovacuum 
configuration? I am stuck because in our case the table gets mostly read 
and if I set up things as to vacuum the table after a specific amount of 
insert/updates, I cannot foresee whether this could happen during 
daytime when server is under high load.
How can I configure the vacuum to run after the daily batch insert/update?
    

It doesn't sound as if your setup is a good match for autovacuum.  You
might be better off going back to the cron vacuums.  That's the
beauty of Postgres -- it gives you the choice.

If you want to continue with autovac, you may want to experiment with
vacuum_cost_delay and associated parameters, which can lessen the
impact of vacuuming.

  

The db is constantly monitored during high peak so that we can switch to a backup pg7.3 database that is being vacuumed every night.
This is giving me the opportunity to try it so I tried this:

vacuum_cost_delay = 200
vacuum_cost_page_hit = 5
vacuum_cost_page_miss = 10
vacuum_cost_page_dirty = 20
vacuum_cost_limit = 100

I know these values affect the normal vacuum process but apparently this means setting
#autovacuum_vacuum_cost_delay = -1      # default vacuum cost delay for
                                        # autovac, -1 means use
                                        # vacuum_cost_delay

and
#autovacuum_vacuum_cost_limit = -1      # default vacuum cost limit for
                                        # autovac, -1 means use
                                        # vacuum_cost_limit


for the rest of them I am currently trying the deafults:

#autovacuum_naptime = 60                # time between autovacuum runs, in secs
#autovacuum_vacuum_threshold = 1000     # min # of tuple updates before vacuum
#autovacuum_analyze_threshold = 500     # min # of tuple updates before analyze
#autovacuum_vacuum_scale_factor = 0.4   # fraction of rel size before vacuum
#autovacuum_analyze_scale_factor = 0.2  # fraction of rel size before analyze

Does anybody know which process is actually AUTO-vacuum-ing the db?
So that I can check when is running...