Re: configure option for XLOG_BLCKSZ

On Fri, May 2, 2008 at 8:50 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Mark Wong" <markwkm(at)gmail(dot)com> writes:
>
> > As someone who has tested varying both those parameters it feels
> > awkward to have a configure option for one and not the other, or vice
> > versa. I have slightly stronger feelings for having them both as
> > configure options because it's easier to script, but feel a little
> > more strongly about having BLCKSZ and XLOG_BLCKSZ both as either
> > configure options or in pg_config_manual.h. To have them such that
> > one needs to change them in different manners makes a tad more work in
> > automating testing. So my case is just for ease of testing.
>
> Well, that's a fair point. Another issue though is whether it makes
> sense for XLOG_BLCKSZ to be different from BLCKSZ at all, at least in
> the default case. They are both the unit of I/O and it's not clear
> why you'd want different units. Mark, has your testing shown any
> indication that they really ought to be separately configurable?
> I could see having the same configure switch set both of 'em.

I still believe it makes sense to have them separated. I did have
some data, which has since been destroyed, that suggested there were
some system characterization differences for OLTP workloads with
PostgreSQL. Let's hope those disks get delivered to Portland soon. :)

Regards,
Mark