OPTIMIZER_ADAPTIVE_PLANS parameter - 19c

OPTIMIZER_ADAPTIVE_PLANS controls adaptive plans. 

Adaptive plans are execution plans built with alternative choices that are decided at run time based on statistics collected as the query executes.

Property	Description
Parameter type	Boolean
Default value	true
Modifiable	ALTER SESSION, ALTER SYSTEM
Modifiable in a PDB	Yes
Range of values	true | false
Basic	No
Oracle RAC	The same value must be set on all instances

Setting this parameter to false disables the following adaptive features:

• Nested loop join/hash join selection

• Star transformation bitmap pruning

• Adaptive parallel distribution method