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.
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/9078678/viewspace-45137/ ，如需转载，请注明出处，否则将追究法律责任。
