OPTIMIZER_MAX_PERMUTATIONS

Parameter type	Integer
Default value	If OPTIMIZER_FEATURES_ENABLE is set to 9.0.0 or higher, then 2000 If OPTIMIZER_FEATURES_ENABLE is set to 8.1.7 or lower, then 80000
Parameter class	Dynamic: ALTER SESSION
Range of values	4 to 80000

OPTIMIZER_MAX_PERMUTATIONS restricts the number of permutations of the tables the optimizer will consider in queries with joins. Such a restriction ensures that the parse time for the query stays within acceptable limits. However, a slight risk exists that the optimizer will overlook a good plan it would otherwise have found.

The default value for this parameter is 80000, which corresponds to no limitation at all. Setting this parameter to a value less than 1000 normally ensures parse times of a few seconds or less.