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by Craig Shallahamer Get the book here |
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Craig Shallahamer's Blog
The text below is an except from the book, Oracle Performance Firefighting, written by Craig Shallahamer of OraPub, Inc. Figures and tables are not included on this page, only their reference. To order the book in either print or PDF form, click here. ©2009, 2010 by Craig Shallahamer. This is copyrighted material. Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. ------------------------------- Now that Oracle has instrumented its code, given the system calls convenient Oracle kernel developer names, stored the timing information, and made the information available in performance views, we are ready to query the wait time through the SQL interface. Oracle makes its kernel instrumentation details available to us very simply through the SQL interface. There is actually a family of wait event views. I will present most of them in this book, starting with the three wait event views that form the core of any wait-based analysis and the queue time component of an ORTA: * v$system_event: This is the high-level view. Like v$sysstat, its contents are reset to zero at instance startup, the values contain summary wait information from all Oracle sessions, and the values increase over time. Please—Out of respect for those involved in the creation of the book and also for their familes, we ask you to respect the copyright both in intent and deed. Thank you. |
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