Tom Lane wrote:
> "P.J. \"Josh\" Rovero" <rovero@sonalysts.com> writes:
>
>>7.4b1 is significantly faster (i.e., the higher curve)
>>over this range of clients and transactions.
>
>
> Cool. I wonder though why the 7.4 curve is so much noisier.
The occurence of postgresql events (WAL recycles, etc) and
system events (reiserfs journal writes, software raid0) isn't
synchronized for each pgbench run. So one or more of the set
of 5 runs for each number of clients/transactions combination
may "suffer" statistically because the backend or system is
performing some other task. The only other user apps
running were "tail -f" on the postgresql and pgbench
logs.
Here is a set (clients (1:1:10), transactions (100:100:1000))
where a vacuum full was done prior to each set of 5 runs.
7.4 is still significantly faster, even though results
are noisier and "degradation" as number of transactions
per client increases is steeper.
