If you enable caching and run a test for a single-table constraint, the PowerCenter Integration Service divides the specified cache size among all Aggregator, Joiner, Lookup, and Sorter transformations in the underlying PowerCenter session. The PowerCenter Integration Service allocates cache memory based on the transformation requirements, such as the number of rows processed, number and types of tests, and precision and scale of the table columns.
For optimal session performance, configure the cache size so that the PowerCenter Integration Service processes each transformation in memory without paging to disk. Session performance decreases when the Integration Service pages to disk. To determine the required cache size for each transformation, review the cache size specified in the session log after the session completes.