> Ok.. I would be surprised if you needed much more actual CPU power. I
> suspect they're mostly idle waiting on data -- especially with a Quad
> Xeon (shared memory bus is it not?).
In reality the CPUs get pegged: about 65% PG and 35% system. But I agree that memory throughput and latency is an
issue.
> Write performance won't matter very much. 3000 inserts/second isn't high
> -- some additional battery backed write cache may be useful but not
> overly important with enough ram to hold the complete dataset. I suspect
> those are slow due to things like foreign keys -- which of course are
> selects.
3000 inserts/sec isn't high when they're inside one transaction, but if each is inside its own transaction then that's
3000
commits/second.
> case, additional ram will keep the system from hitting the disk for
> writes as well.
How does that work?
> You may want to play around with checkpoints. Prevention of a checkpoint
> during this hour will help prevent peaks. Be warned though, WAL will
> grow very large, and recovery time should a crash occur could be
> painful.
Good point. I'll have a think about that.