Remember that as you increase shared_buffers you might need to make the bgwriter more aggressive too. On Thu, Dec 07, 2006 at 11:42:39AM -0500, Bill Moran wrote: > > I'm gearing up to do some serious investigation into performance for > PostgreSQL with regard to our application. I have two issues that I've > questions about, and I'll address them in two seperate emails. > > This one regards tuning shared_buffers. > > I believe I have a good way to monitor database activity and tell when > a database grows large enough that it would benefit from more > shared_buffers: if I monitor the blks_read column of pg_stat_database, > it should increase very slowly if there is enough shared_buffer > space. When shared buffer space runs out, more disk read requests > will be required and this number will begin to climb. > > If anyone sees a flaw in this approach, I'd be interested to hear it. > > The other tuning issue with shared_buffers is how to tell if I'm > allocating too much. For example, if I allocate 1G of RAM to > shared buffers, and the entire database can fit in 100M, that 900M > might be better used as work_mem, or something else. > > I haven't been able to find anything regarding how much of the > shared buffer space PostgreSQL is actually using, as opposed to > simply allocating. > > -- > Bill Moran > Collaborative Fusion Inc. > > wmoran@xxxxxxxxxxxxxxxxxxxxxxx > Phone: 412-422-3463x4023 > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > -- Jim Nasby jim@xxxxxxxxx EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
