Message-ID: <F001.0050028D.20021111095938@fatcity.com>
Date: Mon, 11 Nov 2002 09:59:38 -0800
To: Multiple recipients of list ORACLE-L <ORACLE-L@fatcity.com>
Sender: root@fatcity.com
Reply-To: ORACLE-L@fatcity.com
Errors-To: ML-ERRORS@fatcity.com
From: "Jeffery Stevenson" <dba@darkora.net>
Subject: Re: Is nothing sacred? (Oracle vs The Experts)
Organization: Fat City Network Services, San Diego, California
Precedence: bulk
Mime-Version: 1.0
Content-Type: text/plain;	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

Well, besides the paper you found, Jonathan Lewis has a myths section with
his site:
http://www.jlcomp.demon.co.uk/myths.html

Gaja also has a good "myths" article:
http://www.quest-pipelines.com/newsletter-v3/0302_F.htm

Rachel, weren't you doing a presentation on Oracle myths (or did you just
put that in DBA 101)?

Jeffery Stevenson
Chief Databeast Slayer
Medical Present Value, Inc.
Austin, TX

----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <ORACLE-L@fatcity.com>
Sent: Monday, November 11, 2002 10:58 AM


> So, there I am, on 8.1.7.2 (and .4) on HP/UX 11.0, with a process that
runs
> 20 minutes out of every hour of the day (despite my protests to it's
> design).  After it starts having problems (go figure), it becomes a
priority
> to speed it up.
>
> Thanks to a 10046 trace, we see that the query taking the most elapsed
time
> does FTSs on each of two very small tables (1 block and 4 blocks -- 8K
> blocksize).  These tables are not indexed, as per the official Oracle
> recommendation.  After reading the excellent Hotsos paper "When to index a
> table" (THANKS, CARY!), I added an index to reduce elapsed time on this
> query by 50% (150 to 75 seconds in test), proving to me that the paper is
> valid.  And I've only read to page four!
>
> OK, first I'm taught by Oracle to look at Buffer Cache Hit Ratios as a
> measure of performance, then told (and thoroughly convinced) by experts
that
> this is bunk.  Now, I found out that the 15% (or 10% or whatever,
depending
> on version) ratio of rows returned to total rows in determining when to
use
> an index in a query is garbage.
>
> 1)  Why is this?
>
> 2)  What other pearls of performance wisdom from Oracle Corp should I
> completely disregard as false?
>
> I know there's an Oracle Fallacy website somewhere...
>
> It just looks bad on me, our department, and Oracle when, once again,
> something I've been preaching to our developers as gospel turns out to be
> completely false.
>
> Maybe I'm grumpy because it's snowing on my leaves right now...  <sigh>
>
>
> Rich
>
>
> Rich Jesse                           System/Database Administrator
> Rich.Jesse@qtiworld.com              Quad/Tech International, Sussex, WI
USA
>
> Disclaimer:  I only said the Packers would be 12-4 this year -- I never
said
> that they couldn't do better!  WOO-HOO!  :)
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Jesse, Rich
>   INET: Rich.Jesse@qtiworld.com
>
> Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
> San Diego, California        -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from).  You may
> also send the HELP command for other information (like subscribing).
>
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Jeffery Stevenson
  INET: dba@darkora.net

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).