Call for Oracle support & training (800) 766-1884
Free Oracle Tips

Home
Corporate Oracle Training
Custom Oracle Training
Oracle New Features Training
Advanced Oracle DBA Classes
Oracle Tuning Courses
Oracle Tips & Tricks
Oracle Training Links
Oracle Training Links
Oracle Training Links

We are top for USA Oracle Training Clients

 

Free Oracle Tips


 
HTML Text AOL

Free Oracle App Server Tips


 
HTML Text

Oracle support

Oracle training

Oracle tuning

Rednecks!

Remote Oracle

Custom Oracle Training

Donald K. Burleson

Oracle Tips

Tuning Value of Oracle Buffer Cache Hit Ratio?

The buffer cache hit rationdicates how often data is found in memory vs. disk.  Critics of this ratio complain that it is not a good indicator of performance because (a) many analysts use cumulative numbers for the computations, which can artificially inflate the value to a meaningless measure, and (b) it does not negatively reflect excessive logical I/O activity, which, although faster than disk I/O, can certainly suppress performance on any database. 

These complaints have merit.  One must use delta statistics over time to come up with a meaningful value for the ratio, and high logical I/O values can definitely be a leading cause of bad execution times.  However, when properly computed, the buffer cache hit ratio  is an excellent indicator of how often the data requested by users is found in RAM instead of disk, a fact of no small importance.

The global statistic shown above is a good place to start, but you do not have to stop there.  You can penetrate deeper to find cache hit ratios at the buffer pool, session, and SQL statement level. 


The above is an excerpt from Oracle Performance Troubleshooting by Robin Schumacher.

It's only $19.95 and you can order it and get instant access to the Oracle scripts here:

http://www.rampant-books.com/book_2003_1_perf.htm

 

 

 

 
 
 

Oracle performance tuning book

 

 

Oracle performance tuning software

 
Oracle performance tuning software
 
Oracle performance Tuning 10g reference poster
 
Oracle training in Linux commands
 
Oracle training Excel
 
 
 
 
 
email BC:


Copyright © 1996 -  2014 by Burleson Inc. All rights reserved.

Oracle® is the registered trademark of Oracle Corporation.