1.235 OPTIMIZER_ADAPTIVE_STATISTICS
OPTIMIZER_ADAPTIVE_STATISTICS
controls adaptive statistics. Some query shapes are too complex to rely on base table statistics alone, so the optimizer augments these statistics with adaptive statistics.
Property | Description |
---|---|
Parameter type |
Boolean |
Default value |
|
Modifiable |
|
Modifiable in a PDB |
Yes |
Range of values |
|
Basic |
No |
Oracle RAC |
The same value must be set on all instances |
Setting this parameter to false
disables the following adaptive features:
-
SQL plan directives
-
Statistics feedback for joins
-
Adaptive dynamic sampling for parallel execution
Note:
Setting OPTIMIZER_ADAPTIVE_STATISTICS
to false
preserves the statistics feedback functionality that was introduced in Oracle Database 11g.
OPTIMIZER_ADAPTIVE_STATISTICS
does not control the creation of SQL plan directives. SQL plan directives will be created even if this parameter is false
, but they will not be used to refine SQL execution plans with dynamic sampling.
See Also:
Oracle Database SQL Tuning Guide for information about adaptive plans