| Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-03 |
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View PDF |
| Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-03 |
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|
View PDF |
V$PGA_TARGET_ADVICE_HISTOGRAM predicts how statistics displayed by the V$SQL_WORKAREA_HISTOGRAM dynamic view would be impacted if the value of the PGA_AGGREGATE_TARGET parameter is changed. This prediction is performed for various values of the PGA_AGGREGATE_TARGET parameter, selected around its current value. The advice statistic is generated by simulating the past workload run by the instance.
The content of the view is empty if PGA_AGGREGATE_TARGET is not set. In addition, the content of this view is not updated when the STATISTICS_LEVEL initialization parameter is set to BASIC. Base statistics for this view are reset at instance startup or when the value of the PGA_AGGREGATE_TARGET initialization parameter is dynamically modified.
| Column | Datatype | Description |
|---|---|---|
PGA_TARGET_FOR_ESTIMATE |
NUMBER |
Value of PGA_AGGREGATE_TARGET for this prediction (in bytes) |
PGA_TARGET_FACTOR |
NUMBER |
PGA_TARGET_FOR_ESTIMATE / the current value of the PGA_AGGREGATE_TARGET parameter |
ADVICE_STATUS |
VARCHAR2(3) |
Indicates whether the advice is enabled (ON) or disabled (OFF) depending on the value of the STATISTICS_LEVEL parameter |
LOW_OPTIMAL_SIZE |
NUMBER |
Lower bound for the optimal memory requirement of work areas included in this row (in bytes) |
HIGH_OPTIMAL_SIZE |
NUMBER |
Upper bound for the optimal memory requirement of work areas included in this row (in bytes) |
ESTD_OPTIMAL_EXECUTIONS |
NUMBER |
Number of work areas with an optimal memory requirement comprised between LOW_OPTIMAL_SIZE and HIGH_OPTIMAL_SIZE which are predicted to run optimal given a value of PGA_AGGREGATE_TARGET equal to PGA_TARGET_FOR_ESTIMATE |
ESTD_ONEPASS_EXECUTIONS |
NUMBER |
Number of work areas with an optimal memory requirement comprised between LOW_OPTIMAL_SIZE and HIGH_OPTIMAL_SIZE which are predicted to run one-pass given a value of PGA_AGGREGATE_TARGET equal to PGA_TARGET_FOR_ESTIMATE |
ESTD_MULTIPASSES_EXECUTIONS |
NUMBER |
Number of work areas with an optimal memory requirement comprised between LOW_OPTIMAL_SIZE and HIGH_OPTIMAL_SIZE which are predicted to run multi-pass given a value of PGA_AGGREGATE_TARGET equal to PGA_TARGET_FOR_ESTIMATE |
ESTD_TOTAL_EXECUTIONS |
NUMBER |
Sum of ESTD_OPTIMAL_EXECUTIONS, ESTD_ONEPASS_EXECUTIONS, and ESTD_MULTIPASSES_EXECUTIONS |
IGNORED_WORKAREAS_COUNT |
NUMBER |
Number of work areas with optimal memory requirement between LOW_OPTIMAL_SIZE and HIGH_OPTIMAL_SIZE ignored in the advice generation due to memory and CPU constraints |
See Also:
Oracle Database Performance Tuning Guide for information on tuning the
PGA_AGGREGATE_TARGET initialization parameter using the PGA advice views