When you run a mapping that contains a Rank transformation, Data Integration creates data and index cache files to run the transformation. By default, Data Integration stores the cache files in the directory entered in the Secure Agent $PMCacheDir property for the Data Integration Server.
You can change the cache directory and cache sizes on the Advanced tab of the Rank transformation.
Data Integration creates the following caches for the Rank transformation:
•Data cache that stores row data based on the group by fields.
•Index cache that stores group values as configured in the group by fields.
When you run a mapping that contains a Rank transformation, Data Integration compares an input row with rows in the data cache. If the input row out-ranks a cached row, Data Integration replaces the cached row with the input row. If you configure the Rank transformation to rank across multiple groups, Data Integration ranks incrementally for each group that it finds.
If you create multiple partitions in the Source transformation, Data Integration creates separate caches for each partition.