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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. ------------------------------- The number of redo allocation latches is controlled by the instance parameter processes. Around each eight processes defined, one redo allocation latch is created. Figure 8-5 shows both the query and output (with many output lines removed) of an Oracle Database 10g Release 2 system with 4,000 processes defined. Oracle created 488 redo allocation latches, which amounts to 8.2 processes for each redo allocation latch. This ratio of processes to allocation latches has been observed for many different processes parameter settings. Figure 8-5. Shown is a system with a defined 4,000 Oracle process limit, resulting in 488 redo allocation latches. The system is undergoing an intense three-process DML workload. Now that I've laid the architectural foundation, let's see how this is combined into the flow of redo. 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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