Archive for January, 2012
Nologging redo size
It is probably easy to calculate hourly redo rate or daily redo rate using AWR data. For example, my script awr_redo_size.sql can be used to calculate daily redo rate, and awr_redo_size_history.sql can be used to calculate hourly redo rate. Hourly redo rate is especially useful since you can export to an excel spreadsheet, graph it to see redo rate trend. Introduction to Direct Mode Writes Direct mode operations write directly in to the database file ...
Troubleshooting LMS processes
This was created circa July 2011. Enjoy. [wpvideo mabMGh2o]
SCN – What, why, and how?
In this blog entry, we will explore the wonderful world of SCNs and how Oracle database uses SCN internally. We will also explore few new bugs and clarify few misconceptions about SCN itself. What is SCN? SCN (System Change Number) is a primary mechanism to maintain data consistency in Oracle database. SCN is used primarily in the following areas, of course, this is not a complete list: Every redo record has an SCN version of the redo record ...
GC cr disk read
You might encounter RAC wait event 'gc cr disk read' in 11.2 while tuning your applications in RAC environment. Let's probe this wait event to understand why a session would wait for this wait event. Understanding the wait event Let's say that a foreground process running in node 1, is trying to access a block using a SELECT statement and that block is not in the local cache. To maintain the read consistency, foreground process will require ...
RMOUG 2012 – Hello Denver!
On February 14-16, I’ll be at the Colorado Convention Center in Denver, Colorado for RMOUG’s Training Days Conference. This is the largest regional Oracle User Conference in North America and attracts presenters from all around the country and the globe. I’ll be presenting: Presentation Name: Troubleshooting RAC Background Process Abstract: RAC background process performance is critical to keep the application performance. This session will ...
