Hi all, 2006/10/5, Tom Lane <tgl@xxxxxxxxxxxxx>:
"Peter Bauer" <peter.m.bauer@xxxxxxxxx> writes: > tps = 50.703609 (including connections establishing) > tps = 50.709265 (excluding connections establishing) That's about what you ought to expect for a single transaction stream running on honest disk hardware (ie, disks that don't lie about write complete). You can't commit a transaction more often than once per disk revolution, because you have to wait for the current WAL file endpoint to pass under the heads again. If there are multiple clients then "ganging" concurrent commits is possible, but you tested only one. The benchmark you reference might have been done on disks with battery backed write cache. Or it might have been just plain unsafe (ie, the equivalent of fsync off, but in hardware :-()
You are right, i performed the pgbench tests on another machine with the same hardware but a kernel which supports the onboard Dell Raid Controller with battery backed write cache and the result is about 400 tps. We will see how much difference this makes in practice but at least i know where the "problem" was. thx, Peter
