The Update Synchronizer and some of the Oracle features that

Identity Resolution

uses work only with the cost-based optimizer (CBO). If you have optimized the existing applications to use the rule-based optimizer (RBO), you can enable CBO only for

Identity Resolution

.

To enable CBO for

Identity Resolution

, set the

OPTIMIZER_MODE

initialization parameter to RULE and collect statistics for the USTs. The existing applications continue to use RBO, and when

Identity Resolution

accesses the USTs,

Identity Resolution

specifies the CHOOSE hint. The CHOOSE hint causes the optimizer to choose between RBO and CBO based on the presence of statistics. If statistics exist for any of the USTs,

Identity Resolution

uses the CBO.