March 2007
Intermediate to advanced
488 pages
13h 46m
English
book
OnDemand SQL Performance Analysis Simplified on DB2 for i5/OS in V5R4
by Hernando Bedoya, Jaime Gaug, James Kerl, Ser Ser NG, Jose Cardoso dos Santos
Content preview from OnDemand SQL Performance Analysis Simplified on DB2 for i5/OS in V5R4
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Chapter 10. SQL performance analysis: a methodology 375
In Figure 10-7 we see that the run time has improved from the 66 second time seen in the
plan cache snapshot to less than half a second. Nice work!
Figure 10-7 Nice work
If we step back and think about it, this makes sense. When the database was first created,
the sales table was small and it performed fine without any indexes. But as sales grew and
the size of the table increased, it became more and more expensive to find a particular sales
person’s data within the table. Therefore, the index, keyed by sales person, was just what
was needed.
376 OnDemand SQL Performance Analysis Simplified ...
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