From: Josh Berkus <josh@agliodbs.com>
Organization: Aglio Database Solutions
To: pgsql-performance@postgresql.org
Subject: Re: Read/Write block sizes
Date: Tue, 23 Aug 2005 19:31:29 -0700
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Cc: Steve Poe <spoe@sfnet.cc>, Chris Browne <cbbrowne@acm.org>
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Steve,

> I would assume that dbt2 with STP helps minimize the amount of hours
> someone has to invest to determine performance gains with configurable
> options?

Actually, these I/O operation issues show up mainly with DW workloads, so the 
STP isn't much use there.   If I can ever get some of these machines back 
from the build people, I'd like to start testing some stuff.

One issue with testing this is that currently PostgreSQL doesn't support block 
sizes above 128K.  We've already done testing on that (well, Mark has) and 
the performance gains aren't even worth the hassle of remembering you're on a 
different block size (like, +4%).

What the Sun people have done with other DB systems is show that substantial 
performance gains are possible on large databases (>100G) using block sizes 
of 1MB.   I believe that's possible (and that it probably makes more of a 
difference on Solaris than on BSD) but we can't test it without some hackery 
first.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco