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Oracle® Database Reference
11g Release 2 (11.2)

E40402-10
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OPTIMIZER_DYNAMIC_SAMPLING

Property Description
Parameter type Integer
Default value If OPTIMIZER_FEATURES_ENABLE is set to 10.0.0 or higher, then 2

If OPTIMIZER_FEATURES_ENABLE is set to 9.2.0, then 1

If OPTIMIZER_FEATURES_ENABLE is set to 9.0.1 or lower, then 0

Modifiable ALTER SESSION, ALTER SYSTEM
Range of values 0 to 11
Basic No

OPTIMIZER_DYNAMIC_SAMPLING controls both when the database gathers dynamic statistics, and the size of the sample that the optimizer uses to gather the statistics.

Note:

Dynamic statistics were called dynamic sampling in releases before Oracle Database 11g Release 2 (11.2.0.4).

When this parameter is set to 11, the optimizer will use dynamic statistics to verify cardinality estimates for all SQL operators, and it will determine an internal time limit to spend verifying the estimates.

If the value of OPTIMIZER_DYNAMIC_SAMPLING is set to 11, the OPTIMIZER_FEATURES_ENABLE setting has no effect on the OPTIMIZER_DYNAMIC_SAMPLING setting.

See Also:

Oracle Database Performance Tuning Guide for more information on setting this parameter