Re: [HACKERS] Re: [ADMIN] v7.1b4 bad performance

[Tatsuo Ishii]

> Okay, plan B then: let's ask people to redo their benchmarks with
> -s bigger than one.  Now, how much bigger?
> 
> To the extent that you think this is a model of a real bank, it should
> be obvious that the number of concurrent transactions cannot exceed the
> number of tellers; there should never be any write contention on a
> teller's table row, because only that teller (client) should be issuing
> transactions against it.  Contention on a branch's row is realistic,
> but not from more clients than there are tellers in the branch.
> 
> As a rule of thumb, then, we could say that the benchmark's results are
> not to be believed for numbers of clients exceeding perhaps 5 times the
> scale factor, ie, half the number of teller rows (so that it's not too
> likely we will have contention on a teller row).

At least -s 5 seems reasonable for me too. Maybe we should make it as
the default setting for pgbench?
--
Tatsuo Ishii