Quoth dingxn@xxxxxxxxxxxxxxxxxx (Xiaoning Ding): > When I run multiple TPC-H queries (DBT3) on postgresql, I found the system > is not scalable. My machine has 8GB memory, and 4 Xeon Dual Core processor > ( 8 cores in total). OS kernel is linux 2.6.9. Postgresql is 7.3.18. I > I think it might be caused by some contentions. But I do not know postgresql > much. May anybody give me some clue to find the reasons? Two primary issues: 1. You're running a horrendously ancient version of PostgreSQL. The 7.3 series is Really Old. Newer versions have *enormous* improvements that are likely to be *enormously* relevant. Upgrade to 8.2. 2. There are known issues with the combination of Xeon processors and PAE memory addressing; that sort of hardware tends to be *way* less speedy than the specs would suggest. There have been "context switching" issues on this sort of hardware that are enormously worsened if you're running on a version of PostgreSQL that is 4 major releases out of date. -- wm(X,Y):-write(X),write('@'),write(Y). wm('cbbrowne','gmail.com'). http://cbbrowne.com/info/x.html I am not a number! I am a free man!