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 5. Analyzing SQL performance data using iSeries Navigator 159
Any one of the above items could be focused on to potentially improve performance. Let us
explore them.
5.6.2 Why are table scans being done?
First we will investigate why table scans are occurring for this query. This could definitely be
an area of improvement since we know we are not selecting most of the records in the tables,
and in general table scans are best used when selecting a good portion of the table. Let’s
take a look at the Table Scan Statements report to see why a table scan is being done,
Figure 5-58.
160 OnDemand SQL Performance Analysis Simplified on DB2 f ...
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