Re: Antw: Re: data is skewed - what does it mean ?
Yeah, well them kids are real good at the pointy clicky stuff, and a minority actually know how to do some real programming. But the vast majority of them treat their computers like cars. They know how to drive them, but are clueless about how they work. We're still from outer space. Jared On Thursday 24 July 2003 23:54, Guido Konsolke wrote: Come on, don't try to persuade me of you being old. I'm 42 like you and still feel the blood running through my veins. At least, sometimes ;-) I can remember the (not so) good old times when everyone thought we 'computer wizards' came from outer space. Nowadays almost every school kid has a better equipment at home than me at work. And damagement still wants us to do miracles every single day :( Although it's early morning in Germany: Nice weekend to all list members. Greetings, Guido [EMAIL PROTECTED] 25.07.2003 08.14 Uhr Well, there have been situations when CBO made me use obscene language by stubbornly refusing to use and index which was utilized when RBO was used. I believe that the vast majority of old and balding DBA geezers like me can make the same claims. Thus the name. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jared Still 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).
Re: Antw: Re: data is skewed - what does it mean ?
Hopefully, your analogy will not result in someone's attempt to pour Castrol motor oil in their PC to make it run better. As for being from the outer space, my origins are at Ursa Major. On 2003.07.26 18:39, Jared Still wrote: But the vast majority of them treat their computers like cars. They know how to drive them, but are clueless about how they work. We're still from outer space. Jared -- Mladen Gogala Oracle DBA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala 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).
Re: Antw: Re: data is skewed - what does it mean ?
Hi Mladen, Ursa Major? Have been there some years ago. Beautiful landscape, but too much hairy animals ;-)) But it was just a stop-over on my way to the gamma quadrant with the USS Voyager where I met Seven of Nine. Nice memory 8-))) And about my origins: I have to confess: I was born on this planet, my parents both came from the Wega system and used to work for the Department for Foreign Affairs and have been send to earth to witness the birth of a little boy about 2000 years ago. You can see them in the famous movie 'The Life of Brian'. yadayadayada... hand, Guido [EMAIL PROTECTED] 27.07.2003 01.59 Uhr Hopefully, your analogy will not result in someone's attempt to pour Castrol motor oil in their PC to make it run better. As for being from the outer space, my origins are at Ursa Major. On 2003.07.26 18:39, Jared Still wrote: But the vast majority of them treat their computers like cars. They know how to drive them, but are clueless about how they work. We're still from outer space. Jared -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Guido Konsolke 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).
Re: Antw: Re: data is skewed - what does it mean ?
Ursa Major means great bear. As there is a connection between bears and the nickname that I've had ever since my childhood (no, I'm not going to reveal it), my assumption is that I have, somehow, originated there. On 2003.07.27 00:24, Guido Konsolke wrote: Hi Mladen, Ursa Major? Have been there some years ago. Beautiful landscape, but too much hairy animals ;-)) But it was just a stop-over on my way to the gamma quadrant with the USS Voyager where I met Seven of Nine. Nice memory 8-))) And about my origins: I have to confess: I was born on this planet, my parents both came from the Wega system and used to work for the Department for Foreign Affairs and have been send to earth to witness the birth of a little boy about 2000 years ago. You can see them in the famous movie 'The Life of Brian'. yadayadayada... hand, Guido [EMAIL PROTECTED] 27.07.2003 01.59 Uhr Hopefully, your analogy will not result in someone's attempt to pour Castrol motor oil in their PC to make it run better. As for being from the outer space, my origins are at Ursa Major. On 2003.07.26 18:39, Jared Still wrote: But the vast majority of them treat their computers like cars. They know how to drive them, but are clueless about how they work. We're still from outer space. Jared -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Guido Konsolke 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). -- Mladen Gogala Oracle DBA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala 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).
Re: data is skewed - what does it mean ?
Gogala, If cardinality is high, then data is evenly distributed. If cardinality is low, then data is not evenly distributed and hence skewed. Is my understanding correct...atleast to some extent ?! -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: orababy 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).
Re: Antw: Re: data is skewed - what does it mean ?
Come on, don't try to persuade me of you being old. I'm 42 like you and still feel the blood running through my veins. At least, sometimes ;-) I can remember the (not so) good old times when everyone thought we 'computer wizards' came from outer space. Nowadays almost every school kid has a better equipment at home than me at work. And damagement still wants us to do miracles every single day :( Although it's early morning in Germany: Nice weekend to all list members. Greetings, Guido [EMAIL PROTECTED] 25.07.2003 08.14 Uhr Well, there have been situations when CBO made me use obscene language by stubbornly refusing to use and index which was utilized when RBO was used. I believe that the vast majority of old and balding DBA geezers like me can make the same claims. Thus the name. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Guido Konsolke 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).
Re: data is skewed - what does it mean ?
It's not this simple... Let's take your low cardinality example... Gender is a good example since there are only two (common) genders - male and female. A table with 10,000 staff would make the gender column low cardinaility - only 2 distinct values. If you had 5,000 males and 5,000 females then the data would be evenly distributed and therefore not skewed. If, however, you had 9,500 females and 500 males then you have skewed data. Hopefully this gives some idea of the difference between cardinality and skewed data. orababy [EMAIL PROTECTED]To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] om cc: Sent by: Subject: Re: data is skewed - what does it mean ? [EMAIL PROTECTED] .com 25/07/2003 17:34 Please respond to ORACLE-L Gogala, If cardinality is high, then data is evenly distributed. If cardinality is low, then data is not evenly distributed and hence skewed. Is my understanding correct...atleast to some extent ?! -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: orababy 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). Privileged/Confidential information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such case, you should destroy this message and kindly notify the sender by reply e-mail or by telephone on (61 3) 9612-6999. Please advise immediately if you or your employer does not consent to Internet e-mail for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of Transurban City Link Ltd shall be understood as neither given nor endorsed by it. Privileged/Confidential information may be contained in this message. If you are not the addressee indicated in this message (or responsible for delivery of the message to such person), you may not copy or deliver this message to anyone. In such a case, you should destroy this message and kindly notify the sender by reply e-mail or by telephone on (03) 9612-6999 or (61) 3 9612-6999. Please advise immediately if you or your employer does not consent to Internet e-mail for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of Transurban Infrastructure Developments Limited and CityLink Melbourne Limited shall be understood as neither given nor endorsed by them. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mark Richard INET: [EMAIL PROTECTED] Fat City Network Services-- 858
Re: data is skewed - what does it mean ?
Oh... Thank U Mark. got it now. ...now i can explain it to someone who doesn't know. Cheers. Mark Richard [EMAIL PROTECTED]: It's not this simple... Let's take your low cardinality example... Gender is a good example since there are only two (common) genders - male and female. A table with 10,000 staff would make the gender column low cardinaility - only 2 distinct values. If you had 5,000 males and 5,000 females then the data would be evenly distributed and therefore not skewed. If, however, you had 9,500 females and 500 males then you have skewed data. Hopefully this gives some idea of the difference between cardinality and skewed data. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: orababy 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).
Re: data is skewed - what does it mean ?
It's actually a substitute for another word which is not to be repeated on this list because of the presence of the ladies, much like heck, darn or frigging. It means that the data in the index (you found that word in the chapter about indexes, statistics and the Curses Based Optimizer, am I right) is not distributed evenly, with small variations in the number of rows for any given key, but that there is a small subset of keys which corresponds to significant part of the table. Speaking mathematically, there exists at least one value in the indexed columns so that the number of rows corresponding to this value is significantly larger then the average number of rows per value. In other words, it means that the application relying on such index is skewed up. On 2003.07.25 01:39, orababy wrote: List, Came across ~data is skewed~ while reading the docs. what does it actually mean ? can someone explain this for a novice dba like me. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: orababy 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). -- Mladen Gogala Oracle DBA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala 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).
Antw: Re: data is skewed - what does it mean ?
Hi Mladen, nice one. Never heard that. vbg Still lol, Guido [EMAIL PROTECTED] 25.07.2003 07.54 Uhr (snipped) chapter about indexes, statistics and the Curses Based Optimizer, am I right) (snipped even more) -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Guido Konsolke 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).
Re: Antw: Re: data is skewed - what does it mean ?
Well, there have been situations when CBO made me use obscene language by stubbornly refusing to use and index which was utilized when RBO was used. I believe that the vast majority of old and balding DBA geezers like me can make the same claims. Thus the name. On 2003.07.25 02:04, Guido Konsolke wrote: Hi Mladen, nice one. Never heard that. vbg Still lol, Guido [EMAIL PROTECTED] 25.07.2003 07.54 Uhr (snipped) chapter about indexes, statistics and the Curses Based Optimizer, am I right) (snipped even more) -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Guido Konsolke 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). -- Mladen Gogala Oracle DBA -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala 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).
Re: data is skewed - what does it mean ?
Gogala, so , if there is an index on a column like SEX , then it means data ( in that index ) is skewed. am i right ? for an index , if cardinality is low OR clustering_factor is high -- it means data is skewed. sorry if i sound stupid :-| Is SKEW used with respect to index or table or both ? ..data is the index is not distributed evenly i cannot understand this. index data is not disturbed evenly with respect to ? can u explain ( if possible ) with an example plz ? Mladen Gogala [EMAIL PROTECTED]: It's actually a substitute for another word which is not to be repeated on this list because of the presence of the ladies, much like heck, darn or frigging. It means that the data in the index (you found that word in the chapter about indexes, statistics and the Curses Based Optimizer, am I right) is not distributed evenly, with small variations in the number of rows for any given key, but that there is a small subset of keys which corresponds to significant part of the table. Speaking mathematically, there exists at least one value in the indexed columns so that the number of rows corresponding to this value is significantly larger then the average number of rows per value. In other words, it means that the application relying on such index is skewed up. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: orababy 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).
