Craig Shallahamer's Blog
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You were brought to this page based on an internet search
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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
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©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.
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<p>Surely, 4031 errors are not the only reason to upgrade, but starting with Oracle Database 10g Release 2, Oracle began standardizing memory into 4KB chunks.6 While I would never recommend upgrading to this version only because of this improvement, it may be part of the rationale to upgrade.
</p><p>Just as with standardizing on segment extent sizes, having standard memory chunk sizes increases the likelihood of quickly finding suitable memory. The quicker memory can be found, the fewer CPU cycles will be consumed, the less time the shared pool latch must be held, and the less likely a lot of wasted small chunks of memory will exist (increasing the likelihood of a 4031 error).
</p><p>Oracle itself continues to add new performance features to the core kernel. Sometimes these take the form of new features like a new SQL optimization path. Other times, it means replacing an existing function or algorithm that many kernel developers and most DBAs will be unaware of. One such optimization is the introduction of Oracle's patented in-memory undo (IMU). Essentially, instead of maintaining undo in Oracle segments, the undo is managed, as much as possible, in memory using structures optimized for in-memory operations. But as you will learn, how Oracle does this is fascinating and foreshadows even greater things to come. But with any piece of code, there is always the possibility of a bottleneck, so I'll cover how to detect IMU performance issues and multiple ways to solve the problem (in addition to just turning it off).
</p>
©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.
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