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Re: Re: Physical I/O and databases other than oracle

From: <rgaffuri_at_cox.net>
Date: Thu, 02 Oct 2003 10:14:37 -0800
Message-ID: <F001.005D1D55.20031002101437@fatcity.com>


i guess my question wasnt clear. What Im getting at is do other databases have wait interfaces? Is there architecture such that Physical I/Os are a serious concern. Far more than other bottlenecks. Or is this book just garbage...
>
> From: Daniel Fink <Daniel.Fink_at_Sun.COM>
> Date: 2003/10/02 Thu PM 01:09:36 EDT
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> Subject: Re: Physical I/O and databases other than oracle
>
> This is not an issue of answering the question, but pointing out that the question is not correct.
>
> Why do databases exist (aside to make Larry money)? To 'permanently' store data. As this storage must survive a system failure, we choose to place the data on a non-volatile medium (disk, paper, stone tablets). In order to save and retrieve this data, we need to perform some sort of physical action (write/read). Let's take the telephone system as an example. If we need to look up a phone number, we open the phone book and do a search for the right entry. This can be rather time consuming, especially if we don't know the person's last name or business name. Let's assume we do know the last name, we can get to the proper entry
> fairly quickly, but it still takes some time. Once we have retrieved the information into our memory, we can dial the phone fairly quickly. In this case, the bottleneck is indeed physical i/o. Of course, if we get a busy signal, we can access our memory to redial, completely bypassing the phone book. However, if we are using an old rotary dial phone and we have to make a long distance call, it may take longer to dial the phone than look up the number.
>
> The real question should be "What is the primary bottleneck in presenting data to the user?" In my recent projects, I have found that the database is rarely the bottleneck. I have seen bad code, cpu-starvation, spooling to RAID-5 devices, cartesian products.
>
> Did I mention that I once got an A on an essay test because I argued that the question asked was itself invalid?
>
> Dan
>
> Mladen Gogala wrote:
>
> > On Thu, 2003-10-02 at 11:44, Garry Gillies wrote:
> > > > Im reading an academic book on databases and it states that Physical I/O
> >
> > > Eh?
> > > What IS the primary bottleneck in tuning Oracle?
> >
> > Cache hit ratio. You tune the buffer cache hit ratio (BCHR) and your job
> > is done. Database with 99.9% BCHR must be OK.
> >
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> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Mladen Gogala
> > INET: mladen_at_wangtrading.com
> >
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Received on Thu Oct 02 2003 - 13:14:37 CDT

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