On Wed, Jan 24, 2007 at 02:37:44PM +0900, Galy Lee wrote: > 1. How do we know if autovacuum is enough for my application, or should > I setup a vacuum manually from cron for my application? Generally I trust autovac unless there's some tables where it's critical that they be vacuumed frequently, such as a queue table or a web session table. > 2. How to set the GUC parameters for autovacuum? > There are two sets of parameters for autovacuum: > - vacuum threshold and scale factor (500/0.2) > ?$B!! - analyze threshold and scale factor(250/0.1) > Is there any guideline to set these parameters? When does it need to > change the default values? I find those are generally pretty good starting points; just bear in mind that it means 20% dead space. > 3. How to tune cost-based delay vacuum? > I had searched in performance list; it seems that most of the practices > are based on experience / trial-and-error approach to meet the > requirement of disk utilization or CPU utilization. Is there any other > guild line to set them? Unless you have a means for the database to monitor IO usage on it's own, I don't know that we have a choice... I'll generally start with a cost delay of 20ms and adjust based on IO utilization. -- Jim Nasby jim@xxxxxxxxx EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
