Re: Pgsql 7.4/8.0 on IA64 HP-UX 11i?

On Tuesday August 17 2004 10:38, Tom Lane wrote:
> "Ed L." <pgsql(at)bluepolka(dot)net> writes:
> > $ file `which psql`
> > /opt/pgsql/postgresql-8.0.0beta1/bin/psql: ELF-32 executable object
> > file - IA64
> >
> > This is the same for *many* of the executables in /bin. Does this mean
> > it is a 32-bit executable?
>
> Looks like it to me.
>
> > Does it also, therefore, mean that is not taking
> > advantage of the 64-bit hardware? If so, is there something special I
> > need to pass to pgsql's configure to get it to build 64-bit executables
> > to fully exploit this expensive hardware?
>
> I wouldn't panic. 99% of the value of a 64-bit box for database work
> is that you can handle more than 4Gb worth of RAM for disk cache. Since
> in Postgres's worldview most of the disk caching is supposed to be done
> by the kernel, it really matters not whether the Postgres executables
> think they are 32-bit or 64-bit. All you need is a 64-bit kernel.

The HPUX gurus on http://forums1.itrc.hp.com testify that kernel caches
above approximately 600MB are counter-productive to performance. But we
have 16GB of RAM we definitely want to utilize for caching. Therefore,
we've set the kernel cache to 500MB and now wish to dramatically increase
the size of the PostgreSQL DB cache to take advantage of this RAM, possibly
as large as 8GB for a single cluster.

The Pgsql build scripts are building 32-bit pgsql executables by default,
and thus I'm concerned I'm not going to take advantage of the available RAM
for DB caching.

How do I build 64-bit pgsql executables?
Any concerns about an 8GB shmmax setting?
Other thoughts?

Ed