I am doing to large dataset performance tests with 7.3.4b2 today and I noticed an interesting phenomenon. My shared memory buffers are set at 128MB. Peak postmaster usage appears to be around 90MB.
My test app performs inserts across 4 related tables, each set of 4 inserts representing a single theoretical "device" object. I report how many "devices" I have inserted, per second, for example... [...] 41509 devices inserted, 36/sec [1 second later] 41544 devices inserted, 35/sec [...] (to be clear, 41509 devices inserted equals 166036 actual, related rows in the db) Performance follows an odd "peak and valley" pattern. It will start out with a high insertion rate (commits are performed after each "device set"), then after a few thousand device sets, performance will drop to 1 device/second for about 5 seconds. Then it will slowly ramp up over the next 10 seconds to /just below/ the previous high water mark. A few thousand inserts later, it will drop to 1 device/second again for 5 seconds, then slowly ramp up to just below the last high water mark. Ad infinitum. I am wondering: 1) What am I seeing here? This is on a 4-processor machine and postmaster has a CPU all to itself, so I ruled out processor contention. 2) Is there more performance tuning I could perform to flatten this out, or is this just completely normal? Postmaster never busts over 100MB out of the 128MB shared memory I've allocated to it, and according to <mumble mumble webpage mumble>, this is just about perfect for shared memory settings (100 to 120% high water mark). Thanks. --- Clay Cisco Systems, Inc. [EMAIL PROTECTED] (972) 813-5004 I've stopped 19,647 spam messages. You can too! One month FREE spam protection at http://www.cloudmark.com/spamnetsig/} ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
