Marlene and I did "exploding the myths" a while back and Jeremiah Wilton did a myths presentation at OOW last year as well.
Rachel --- Jeffery Stevenson <[EMAIL PROTECTED]> wrote: > 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" <[EMAIL PROTECTED]> > 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 > > [EMAIL PROTECTED] 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: [EMAIL PROTECTED] > > > > 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: [EMAIL PROTECTED] (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: [EMAIL PROTECTED] > > 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: [EMAIL PROTECTED] (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). __________________________________________________ Do you Yahoo!? U2 on LAUNCH - Exclusive greatest hits videos http://launch.yahoo.com/u2 -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Rachel Carmichael INET: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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).
