Re: Read/Write block sizes - Mailing list pgsql-performance

From Josh Berkus
Subject Re: Read/Write block sizes
Date
Msg-id 200508231931.29682.josh@agliodbs.com
Whole thread Raw
In response to Re: Read/Write block sizes  (Steve Poe <spoe@sfnet.cc>)
Responses Re: Read/Write block sizes
Re: Read/Write block sizes
List pgsql-performance
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

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