> Yutaka tanida <yutaka@nonsensecorner.com> writes:
> > xoror@infuse.org wrote:
> >> does pgbench test with relatively large sequential scans?
>
> > Probably no.
>
> pgbench tries to avoid any seqscans at all, I believe, so it wouldn't be
> very useful for testing a method that's mainly intended to prevent
> seqscans from blowing out the cache.
>
> I tried to implement LRU-2 awhile ago, and got discouraged when I
> couldn't see any performance improvement. But I was using pgbench as
> the test case, and failed to think about its lack of seqscans.
>
> We could probably resurrect that code for comparison to 2Q, if anyone
> can devise more interesting benchmark cases to test.
>
> BTW, when you were running your test case, what shared_buffers did you
> use?
It's very easy to test sequencial scans using pgbench: just drop the
index from account table. I am using this technique to generate heavy
loads.
--
Tatsuo Ishii