On Sat, 15 Dec 2007, okparanoid@xxxxxxx wrote:
First when i run htop i see that the memory used is never more than 150 MB. I don't understand in this case why setting shmall and shmmax kernel's parameters to 16 GB of memory (the server has 32 GB) increase the rapidity of the transaction a lot compared to a shmall and shmax in (only) 2 GB ?!
The kernel parameters provide an upper limit for how much memory PostgreSQL can allocate, but by themselves they don't actually request more memory. There is a configuration parameters called shared_buffers that is the main thing to adjust. Since you say you're new to this, see http://www.westnet.com/~gsmith/content/postgresql/pg-5minute.htm for the first set of things you should be adjusting.
If you're doing lots of updates, you'll need to increase checkpoint_segments as well. Once you get the memory allocated and checkpoint parameters in the right range, at that point you'll be prepared to look into transaction grouping and application issues in that area.
-- * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@xxxxxxxxxxxxxx so that your message can get through to the mailing list cleanly
