Chris Hoover <revoohc@xxxxxxxxx> writes: > there is 1 exception. Everytime there is work to do, it seems to spike our > load from < 1 to a load of 3+ for a short time. This tends to cause > significant slowdowns for our customer if they happen to do anything that is > causing the database to access the drives. It does not seem to matter how > much work there is to do. Cleaning up 1 page/tuple or 15000 page/tuples > tends to cause this spike. No surprise, because vacuum has to read every page of the table to see if there is anything there to clean up. > We are running 7.3.4 on Dell 2650 connected to a Dell powervault running > raid5. If you were running something a little newer (8.0) you could use the vacuum_cost_delay knobs to reduce vacuum's impact on I/O load. regards, tom lane
