Every SQL transaction performed on an Oracle database has various costs associated with it, and these costs are each measured in their own units. Predictive Diagnostics can use these cost metrics to identify SQL statements whose future performance may not scale adequately as data volumes and SQL execution rates increase.
However, a SQL statement whose performance DOES scale adequately with respect to one cost metric (CPU time, for example) may not scale adequately with respect to another (Disk Reads).
For this reason, you can use Predictive Diagnostics to view performance predictions for a number of different cost metrics. The types of cost that can be analyzed via Predictive Diagnostics include:
|
Cost metric |
Description |
|---|---|
|
CPU Time |
The amount of CPU time spent processing the SQL statement. |
|
Disk Reads |
The number of physical disk reads recorded against the SQL statement. |
|
Elapsed Time |
The amount of elapsed time (including wait time) taken to execute the SQL statement. |
|
Logical Reads |
The number of logical reads (buffer gets) retrieved by the SQL statement. |
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