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Oracle® Database Reference
12c Release 1 (12.1)

E17615-24
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V$PGA_TARGET_ADVICE_HISTOGRAM

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
CON_ID NUMBER The ID of the container to which the data pertains. Possible values include:
  • 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs.

  • 1: This value is used for rows containing data that pertain to only the root

  • n: Where n is the applicable container ID for the rows containing data


See Also: