If you need to debug the mapping and you set the tracing level to Verbose, you may experience significant performance degradation when you run the mapping. Do not use Verbose tracing when you tune performance. The mapping tracing level overrides any transformation-specific tracing levels within the mapping. This is not recommended as a long-term response to high levels of transformation errors.

You set the optimizer level for a mapping in the mapping configuration or mapping deployment properties. The Data Integration Service applies different optimizer levels to the mapping depending on how you run the mapping.

The cost-based optimization method causes the Data Integration Service to evaluate a mapping, generate semantically equivalent mappings, and run the mapping with the best performance. This method is most effective for mappings that contain multiple Joiner transformations. It reduces run time for mappings that perform adjacent, unsorted, inner-join operations.

Semantically equivalent mappings are mappings that perform identical functions and produce the same results. To generate semantically equivalent mappings, the Data Integration Service divides the original mapping into fragments. The Data Integration Service then determines which mapping fragments it can optimize.