In response to Edoardo Ceccarelli <eddy@xxxxxx>: > Hello, > > we are running a 7.3 postgres db with only a big table (avg > 500.000records) and 7 indexes for a search engine. > we have 2 of this databases and we can switch from one to another. > Last week we decided to give a try to 8.1 on one of them and everything > went fine, db is faster (about 2 or 3 times in our case) and the server > load is higher - which should mean that faster response time is achieved > by taking a better use of the server. > > We also activated the autovacuum feature to give it a try and that's > were our problems started. > I left the standard autovacuum configuration just to wait and see, pg > decided to start a vacuum on the table just midday when users were > launching search queries on the table and server load reached a very > high value so that in a couple of minutes the db was unusable > > With pg7.3 we use to vacuum the db night time, mostly because the insert > and updates in this table is made in a batch way: a single task that > puts 100.000 records in the db in 10/20minutes, so the best time to > actually vacuum the db would be after this batch. > > 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. -- Bill Moran Collaborative Fusion Inc.
