I wonder if thats something to think about adding to Postgresql? A
setting for multiblock read count like Oracle (Although having said
that I believe that Oracle natively caches pages much more
aggressively that postgresql, which allows the OS to do the file
caching).
Alex Turner
netEconomist
P.S. Oracle changed this with 9i, you can change the Database block
size on a tablespace by tablespace bassis making it smaller for OLTP
tablespaces and larger for Warehousing tablespaces (at least I think
it's on a tablespace, might be on a whole DB).
On 4/19/05, Jim C. Nasby <decibel@decibel.org> wrote:
> On Mon, Apr 18, 2005 at 06:41:37PM -0000, Mohan, Ross wrote:
> > Don't you think "optimal stripe width" would be
> > a good question to research the binaries for? I'd
> > think that drives the answer, largely. (uh oh, pun alert)
> >
> > EG, oracle issues IO requests (this may have changed _just_
> > recently) in 64KB chunks, regardless of what you ask for.
> > So when I did my striping (many moons ago, when the Earth
> > was young...) I did it in 128KB widths, and set the oracle
> > "multiblock read count" according. For oracle, any stripe size
> > under 64KB=stupid, anything much over 128K/258K=wasteful.
> >
> > I am eager to find out how PG handles all this.
>
> AFAIK PostgreSQL requests data one database page at a time (normally
> 8k). Of course the OS might do something different.
> --
> Jim C. Nasby, Database Consultant decibel@decibel.org
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