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

Hannu Krosing <hannu@tm.ee> writes:
> Is this unmodified pgbench or has it Hiroshi tweaked behaviour of
> connecting each client to its own database, so that locking and such
> does not shade the possible benefits (was it about 15% ?) of delay>1

I didn't much like that approach to altering the test, since it also
means that all the clients are working with separate tables and hence
not able to share read I/O; that doesn't seem like it's the same
benchmark at all.  What would make more sense to me is to increase the
number of rows in the branches table.

Right now, at the default "scale factor" of 1, pgbench makes tables of
these sizes:

accounts    100000
branches    1
history        0        (filled during test)
tellers        10

It seems to me that the branches table should have at least 10 to 100
entries, and tellers about 10 times whatever branches is.  100000
accounts rows seems enough though.

Making such a change would render results not comparable with the prior
pgbench, but that would be true with Hiroshi's change too.

Alternatively we could just say that we won't believe any numbers taken
at scale factors less than, say, 10, but I doubt we really need
million-row accounts tables in order to learn anything...

            regards, tom lane