Hi list, I've got a heavily-updated table, and about 30 customers on the same system each with his own version of the table. The 3 configured autovacuum workers take turns vacuuming the table in each customer db; autovacuum is never idle and takes a large part of the available IO.
Fearing that vacuuming might accumulate lateness and hoping to see the system idle every now and then, I increased autovacuum_vacuum_cost_limit to 500 and decreased autovacuum_vacuum_cost_delay to 10. First question : is it an intelligent thing to do or am I better off ignoring the constant vacuuming and trusting that things will get done in time ? With the new settings, autovacuum is still constant (even though each one takes less time), but I'm wary of making autovacuum even less "io-nice". Second thing : the vacuumed tables+indexes taken together are bigger than the available OS disk cache. Does vacuuming them fill the cache, or is there some kind of O_DIRECT in use ? I have a feeling (very un-verified) that this is not the most usefull data I could have in my cache. This is all on PG 8.3. I know upgrading would improve things (particularly since a large percentage of the table remains static between vacuums), but we're still too busy for that right now (unless you tell me I'm going to see a night-and-day difference regarding this particular issue). Thanks. -- Vincent de Phily -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
