From: Rodrigo Madera <rodrigo.madera@gmail.com>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: Ron <rjpeace@earthlink.net>
Cc: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: strange performance regression between 7.4 and 8.1
Date: Thu, 8 Mar 2007 09:23:49 -0300
Message-ID: <3cf983d0703080423x7d2e57d4w52d883f6812d3031@mail.gmail.com> (raw)
In-Reply-To: <a728f9f90703061011m7d7165b5t70d0f17b6391b096@mail.gmail.com>
References: <a728f9f90703011240r9657ac5ra7361fdfdc55c10f@mail.gmail.com>
<2D7248A6-38DB-4FE2-A570-6476D5985E85@event-s.net>
<a728f9f90703051856s2562f4a4g2fd0ba59f3b97609@mail.gmail.com>
<26FE4DE3-7896-4A8F-B26A-4FCDA1890078@event-s.net>
<a728f9f90703060725u56b902e7s64ede481536433de@mail.gmail.com>
<E1HOczX-0007ua-CZ@elasmtp-banded.atl.sa.earthlink.net>
<a728f9f90703061011m7d7165b5t70d0f17b6391b096@mail.gmail.com>
I would just like to note here that this is an example of inefficient
strategy.
We could all agree (up to a certain economical point) that Alex saved the
most expensive one thousand dollars of his life.
I don't know the financial status nor the size of your organization, but I'm
sure that you have selected the path that has cost you more.
In the future, an investment on memory for a (let's say) rather small
database should be your first attempt.
Yours,
Rodrigo Madera
On 3/6/07, Alex Deucher <alexdeucher@gmail.com> wrote:
>
> On 3/6/07, Ron <rjpeace@earthlink.net> wrote:
> > At 10:25 AM 3/6/2007, Alex Deucher wrote:
> > >On 3/5/07, Guido Neitzer <lists@event-s.net> wrote:
> > >>On 05.03.2007, at 19:56, Alex Deucher wrote:
> > >>
> > >> > Yes, I started setting that up this afternoon. I'm going to test
> that
> > >> > tomorrow and post the results.
> > >>
> > >>Good - that may or may not give some insight in the actual
> > >>bottleneck. You never know but it seems to be one of the easiest to
> > >>find out ...
> > >
> > >Well, the SAN appears to be the limiting factor. I set up the DB on
> > >the local scsi discs (software RAID 1) and performance is excellent
> > >(better than the old server). Thanks for everyone's help.
> > >
> > >Alex
> >
> > What kind of SAN is it and how many + what kind of HDs are in it?
> > Assuming the answers are reasonable...
> >
>
> It's a Hitachi WMS/Tagmastore. 105 hitachi SATA drives; 4 Gbps FC.
>
> > Profile the table IO pattern your workload generates and start
> > allocating RAID sets to tables or groups of tables based on IO pattern.
> >
> > For any table or group of tables that has a significant level of
> > write IO, say >= ~25% of the IO mix, try RAID 5 or 6 first, but be
> > prepared to go RAID 10 if performance is not acceptable.
> >
>
> Right now it's designed for max capacity: big RAID 5 groups. I expect
> I'll probably need RAID 10 for decent performance.
>
> > Don't believe any of the standard "lore" regarding what tables to put
> > where or what tables to give dedicated spindles to.
> > Profile, benchmark, and only then start allocating dedicated resources.
> > For instance, I've seen situations where putting pg_xlog on its own
> > spindles was !not! the right thing to do.
> >
>
> Right. Thanks for the advice. I'll post my results when I get around
> to testing some new SAN configurations.
>
> Alex
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
>
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: rodrigo.madera@gmail.com, alexdeucher@gmail.com, rjpeace@earthlink.net
Subject: Re: strange performance regression between 7.4 and 8.1
In-Reply-To: <3cf983d0703080423x7d2e57d4w52d883f6812d3031@mail.gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox