Re: Correct way to accuse BCHR tuning method (Was: Hit ratio)
And I think it's important to realise that ratios are useless as a starting point in the tuning process on any system, not only Oracle. Most OS'es and databases use not instrumented correctly to deal with response time measurements (makes you wonder: If response TIME is what matters, how can you then not measure exactly that - time?) - so in the other worlds (Unix, VMS, Windows, SQL Server, MySQL, DB2) people still beleive in the ratios because they have nothing better. Mogens Anjo Kolk wrote: BCHR tuning is useless as a starting point in the tuning process. Anjo. -Original Message- Yong Huang Sent: Wednesday, December 24, 2003 6:09 PM To: Multiple recipients of list ORACLE-L [This message is not technical, but educational. Readers interested in technical info only may want to skip] Hi, Cary and Gopal, My last message is misunderstood. Nowadays most DBAs that still use buffer cache hit ratio as a primary performance tuning method are those that rarely browse public forums. When we convince them that's a wrong method, we should not say Look. I can bump up BCHR to an arbitrary value. If he doesn't think, he'll say Indeed. If I can get any value, it must be rubbish. But if he's a logical person and thinks for a few minutes, he'll say It's unfair to run that choose_a_hit_ratio program to get an arbitrary hit ratio and say the method is wrong, because you can use the same logic to write a program to get an arbitrary library cache hit ratio, OS in-core inode cache hit ratio or directory name cache hit... My last message is not meant to revive the outdated and probably never correct tuning method. Instead it's meant to let oracle-l members know that when you need to convince those DBAs that still use that method, you need to accuse the BCHR method for correct reason, namely, BCHR does not contain sufficient information for tuning, not because you can raise its value by constantly scanning a table in Oracle; you won't be able to convince some stubbon DBAs who enjoy thinking in a quiet place. I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. Yong Huang __ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?ISO-8859-1?Q?Mogens_N=F8rgaard?= 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
Yep. Simple example: Even though it seems to be sometimes a little on the 'random' side, the ELAPSED_TIME column on V$SQL in v9 is an absolute god send... Cheers Connor --- Mogens_Nørgaard [EMAIL PROTECTED] wrote: And I think it's important to realise that ratios are useless as a starting point in the tuning process on any system, not only Oracle. Most OS'es and databases use not instrumented correctly to deal with response time measurements (makes you wonder: If response TIME is what matters, how can you then not measure exactly that - time?) - so in the other worlds (Unix, VMS, Windows, SQL Server, MySQL, DB2) people still beleive in the ratios because they have nothing better. Mogens Anjo Kolk wrote: BCHR tuning is useless as a starting point in the tuning process. Anjo. -Original Message- Yong Huang Sent: Wednesday, December 24, 2003 6:09 PM To: Multiple recipients of list ORACLE-L [This message is not technical, but educational. Readers interested in technical info only may want to skip] Hi, Cary and Gopal, My last message is misunderstood. Nowadays most DBAs that still use buffer cache hit ratio as a primary performance tuning method are those that rarely browse public forums. When we convince them that's a wrong method, we should not say Look. I can bump up BCHR to an arbitrary value. If he doesn't think, he'll say Indeed. If I can get any value, it must be rubbish. But if he's a logical person and thinks for a few minutes, he'll say It's unfair to run that choose_a_hit_ratio program to get an arbitrary hit ratio and say the method is wrong, because you can use the same logic to write a program to get an arbitrary library cache hit ratio, OS in-core inode cache hit ratio or directory name cache hit... My last message is not meant to revive the outdated and probably never correct tuning method. Instead it's meant to let oracle-l members know that when you need to convince those DBAs that still use that method, you need to accuse the BCHR method for correct reason, namely, BCHR does not contain sufficient information for tuning, not because you can raise its value by constantly scanning a table in Oracle; you won't be able to convince some stubbon DBAs who enjoy thinking in a quiet place. I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. Yong Huang __ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?ISO-8859-1?Q?Mogens_N=F8rgaard?= 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). = Connor McDonald web: http://www.oracledba.co.uk web: http://www.oaktable.net email: [EMAIL PROTECTED] GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day Yahoo! Messenger - Communicate instantly...Ping your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?iso-8859-1?q?Connor=20McDonald?= 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
I think Dave Ensor, at the recent UKOUG conference, called it his portable tuning kit: select elapsed_time, cpu_time from v$sql order by elapsed_time; Mogens Connor McDonald wrote: Yep. Simple example: Even though it seems to be sometimes a little on the 'random' side, the ELAPSED_TIME column on V$SQL in v9 is an absolute god send... Cheers Connor --- Mogens_Nørgaard [EMAIL PROTECTED] wrote: And I think it's important to realise that ratios are useless as a starting point in the tuning process on any system, not only Oracle. Most OS'es and databases use not instrumented correctly to deal with response time measurements (makes you wonder: If response TIME is what matters, how can you then not measure exactly that - time?) - so in the other worlds (Unix, VMS, Windows, SQL Server, MySQL, DB2) people still beleive in the ratios because they have nothing better. Mogens Anjo Kolk wrote: BCHR tuning is useless as a starting point in the tuning process. Anjo. -Original Message- Yong Huang Sent: Wednesday, December 24, 2003 6:09 PM To: Multiple recipients of list ORACLE-L [This message is not technical, but educational. Readers interested in technical info only may want to skip] Hi, Cary and Gopal, My last message is misunderstood. Nowadays most DBAs that still use buffer cache hit ratio as a primary performance tuning method are those that rarely browse public forums. When we convince them that's a wrong method, we should not say Look. I can bump up BCHR to an arbitrary value. If he doesn't think, he'll say Indeed. If I can get any value, it must be rubbish. But if he's a logical person and thinks for a few minutes, he'll say It's unfair to run that choose_a_hit_ratio program to get an arbitrary hit ratio and say the method is wrong, because you can use the same logic to write a program to get an arbitrary library cache hit ratio, OS in-core inode cache hit ratio or directory name cache hit... My last message is not meant to revive the outdated and probably never correct tuning method. Instead it's meant to let oracle-l members know that when you need to convince those DBAs that still use that method, you need to accuse the BCHR method for correct reason, namely, BCHR does not contain sufficient information for tuning, not because you can raise its value by constantly scanning a table in Oracle; you won't be able to convince some stubbon DBAs who enjoy thinking in a quiet place. I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. Yong Huang __ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?ISO-8859-1?Q?Mogens_N=F8rgaard?= 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). = Connor McDonald web: http://www.oracledba.co.uk web: http://www.oaktable.net email: [EMAIL PROTECTED] GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day Yahoo! Messenger - Communicate instantly...Ping your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: =?ISO-8859-1?Q?Mogens_N=F8rgaard?= 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
Hi Yong I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. The thing is most people who have used this demonstration, use it for 2 reasons 1. It is immediately recognised and empathised with by the audience and 2. It is easily explained. How does it work, by doing pointless io, hmmm I wonder if that is a problem with my real system. You are of course in principle correct that one could use the same technique against other ratios, my suggestion would be that this might also be appropriate for similar reasons. My CPU is 75% utilized on my web server, I wonder does this mean it is well specified or that I am doing pointless cpu work? If people are merely saying the bchr is useless, here is a script that will create one for you then I would agree with you, but in my experience the argument is more cogent than that. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
#1. what is the difference in the 4 BCHR's in 9i? #2. How do you determine whether your buffer cache is sized properly? - Original Message - To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Sent: Saturday, December 27, 2003 9:34 AM Hi Yong I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. The thing is most people who have used this demonstration, use it for 2 reasons 1. It is immediately recognised and empathised with by the audience and 2. It is easily explained. How does it work, by doing pointless io, hmmm I wonder if that is a problem with my real system. You are of course in principle correct that one could use the same technique against other ratios, my suggestion would be that this might also be appropriate for similar reasons. My CPU is 75% utilized on my web server, I wonder does this mean it is well specified or that I am doing pointless cpu work? If people are merely saying the bchr is useless, here is a script that will create one for you then I would agree with you, but in my experience the argument is more cogent than that. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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.net -- Author: Ryan 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
#1. what is the difference in the 4 BCHR's in 9i? What do you mean by that? Are you refferring to different buffer pool stats here? #2. How do you determine whether your buffer cache is sized properly? Your application meets it's defined operational response time and throughput constraints. Tanel. - Original Message - To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Sent: Saturday, December 27, 2003 9:34 AM Hi Yong I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. The thing is most people who have used this demonstration, use it for 2 reasons 1. It is immediately recognised and empathised with by the audience and 2. It is easily explained. How does it work, by doing pointless io, hmmm I wonder if that is a problem with my real system. You are of course in principle correct that one could use the same technique against other ratios, my suggestion would be that this might also be appropriate for similar reasons. My CPU is 75% utilized on my web server, I wonder does this mean it is well specified or that I am doing pointless cpu work? If people are merely saying the bchr is useless, here is a script that will create one for you then I would agree with you, but in my experience the argument is more cogent than that. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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.net -- Author: Ryan 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.net -- Author: Tanel Poder 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
#2. How do you determine whether your buffer cache is sized properly? Your application meets it's defined operational response time and throughput constraints. Actually that is an interesting answer, since it doesn't answer the question asked 'How do I know if my buffer cache is sized properly' but a much better question which is something like 'how do I know if my application is tuned sufficiently?', or to borrow Gaja's CTD idea 'How do I know when to stop tuning?'. I don't know if other nations have hi-fi buffs (though I guess so) who obsess about the quality of the interconnects, the balance of the turntable, the merits of the pre-amp etc etc. I imagine them as conducting 'tuning' enquiries along the lines of 'how do I know if my speaker cables are performing optimally?' when a much much better question would be 'Why am I listening to Lionel Richie anyway?'. Asking the right questions is a key skill for DBAs it seems to me. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
Performance 'problems' are dependent on what the marketing department gets in the SLA. So if your marketing guys negotiate very strict response time requirements and you dont meet them, then you have a performance problem. How do I know if my buffer cache is having any effect on that? - Original Message - To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Sent: Saturday, December 27, 2003 4:24 PM #2. How do you determine whether your buffer cache is sized properly? Your application meets it's defined operational response time and throughput constraints. Actually that is an interesting answer, since it doesn't answer the question asked 'How do I know if my buffer cache is sized properly' but a much better question which is something like 'how do I know if my application is tuned sufficiently?', or to borrow Gaja's CTD idea 'How do I know when to stop tuning?'. I don't know if other nations have hi-fi buffs (though I guess so) who obsess about the quality of the interconnects, the balance of the turntable, the merits of the pre-amp etc etc. I imagine them as conducting 'tuning' enquiries along the lines of 'how do I know if my speaker cables are performing optimally?' when a much much better question would be 'Why am I listening to Lionel Richie anyway?'. Asking the right questions is a key skill for DBAs it seems to me. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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.net -- Author: Ryan 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ryan Sent: 27 December 2003 21:59 To: Multiple recipients of list ORACLE-L Subject: Re: Correct way to accuse BCHR tuning method (Was: Hit ratio) Performance 'problems' are dependent on what the marketing department gets in the SLA. So if your marketing guys negotiate very strict response time requirements and you dont meet them, then you have a performance problem. How do I know if my buffer cache is having any effect on that? Build a profile of what the app is doing. If it is spending a significant proportion of its time waiting on physical IO then *maybe* your cache is badly sized (most likely you are doing too much IO though). Even here though (and in my experience others may have different views) your first target will be to reduce the IO before you throw memory at the problem. Niall -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Niall Litchfield 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
#2. How do you determine whether your buffer cache is sized properly? Your application meets it's defined operational response time and throughput constraints. Actually that is an interesting answer, since it doesn't answer the question asked 'How do I know if my buffer cache is sized properly' but a much better Well, IF Your application meets it's defined operational response time and throughput constraints THEN your buffer cache is sized properly (as everything else) AND one stop worrying about it. Anyway, don't take my posts in threads containing BCHR's too seriously ;) Tanel. -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
Yong, The point I want to make is that the buffer cache hit ratio actually *is* useful, in the following way. If its value is greater than about 99%, then I can practically guarantee that there is some high-LIO SQL inside the application whose repair will greatly improve system performance. Connor's script is a neat means of jarring someone out of the belief that a good hit ratio necessarily indicates good performance. Cary Millsap Hotsos Enterprises, Ltd. http://www.hotsos.com Upcoming events: - Performance Diagnosis 101: 1/27 Atlanta - SQL Optimization 101: 2/16 Dallas - Hotsos Symposium 2004: March 7-10 Dallas - Visit www.hotsos.com for schedule details... -Original Message- Yong Huang Sent: Wednesday, December 24, 2003 11:09 AM To: Multiple recipients of list ORACLE-L [This message is not technical, but educational. Readers interested in technical info only may want to skip] Hi, Cary and Gopal, My last message is misunderstood. Nowadays most DBAs that still use buffer cache hit ratio as a primary performance tuning method are those that rarely browse public forums. When we convince them that's a wrong method, we should not say Look. I can bump up BCHR to an arbitrary value. If he doesn't think, he'll say Indeed. If I can get any value, it must be rubbish. But if he's a logical person and thinks for a few minutes, he'll say It's unfair to run that choose_a_hit_ratio program to get an arbitrary hit ratio and say the method is wrong, because you can use the same logic to write a program to get an arbitrary library cache hit ratio, OS in-core inode cache hit ratio or directory name cache hit... My last message is not meant to revive the outdated and probably never correct tuning method. Instead it's meant to let oracle-l members know that when you need to convince those DBAs that still use that method, you need to accuse the BCHR method for correct reason, namely, BCHR does not contain sufficient information for tuning, not because you can raise its value by constantly scanning a table in Oracle; you won't be able to convince some stubbon DBAs who enjoy thinking in a quiet place. I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. Yong Huang __ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Yong Huang 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.net -- Author: Cary Millsap 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: Correct way to accuse BCHR tuning method (Was: Hit ratio)
BCHR tuning is useless as a starting point in the tuning process. Anjo. -Original Message- Yong Huang Sent: Wednesday, December 24, 2003 6:09 PM To: Multiple recipients of list ORACLE-L [This message is not technical, but educational. Readers interested in technical info only may want to skip] Hi, Cary and Gopal, My last message is misunderstood. Nowadays most DBAs that still use buffer cache hit ratio as a primary performance tuning method are those that rarely browse public forums. When we convince them that's a wrong method, we should not say Look. I can bump up BCHR to an arbitrary value. If he doesn't think, he'll say Indeed. If I can get any value, it must be rubbish. But if he's a logical person and thinks for a few minutes, he'll say It's unfair to run that choose_a_hit_ratio program to get an arbitrary hit ratio and say the method is wrong, because you can use the same logic to write a program to get an arbitrary library cache hit ratio, OS in-core inode cache hit ratio or directory name cache hit... My last message is not meant to revive the outdated and probably never correct tuning method. Instead it's meant to let oracle-l members know that when you need to convince those DBAs that still use that method, you need to accuse the BCHR method for correct reason, namely, BCHR does not contain sufficient information for tuning, not because you can raise its value by constantly scanning a table in Oracle; you won't be able to convince some stubbon DBAs who enjoy thinking in a quiet place. I agree that It's not the ratio that needs condemning, it's the advice about... What I disagree is the wrong educational tool people on public forums have recently used again and again to show the inadequacy of the BCHR tuning method. Yong Huang __ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/ -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Yong Huang 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.net -- Author: Anjo Kolk 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).
