Craig Shallahamer's Blog
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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.
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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>While the improvement seems dramatic, only when users trigger multiple and serial executing SQL statements are they likely to feel any difference. Additionally, total sample interval Oracle CPU consumption is 1,257 seconds (Figure 9-27), so a decrease of around 230 seconds may not result in much of a utilization improvement. But let's do the math, create the index, and see what happens.
</p><p>Subtracting the CPU consumption from the statements shown in Table 9-3 (230.553 seconds), and then adding back their tuned CPU consumption of 0.0231 second, the expected Oracle CPU consumption becomes 1,026.948 seconds (1257.478 -230.553 + 0.023). Placing the expected CPU consumption into the standard utilization formula, we see the expected utilization is about 14%.
</p><p>As shown in Figure 9-28, Oracle consumed 17% of the available CPU. By creating the status index, we expect Oracle to consume about 14% of the available CPU. So what seemed like a massive improvement that would certainly change the performance situation, is actually expected to result in only a 3% CPU utilization savings. To see what actually occurred when the index was added, read on!
</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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