The Integration Service uses cache memory to process Sorter transformations. The Integration Service passes all incoming data into the Sorter transformation before it performs the sort operation.

The Integration Service creates a sorter cache to store sort keys and data while the Integration Service sorts the data. By default, the Integration Service creates one memory cache and disk cache for all partitions.

If you create multiple partitions in the session, the Integration Service uses cache partitioning. It creates one disk cache for the Sorter transformation and one memory cache for each partition. The Integration Service creates a separate cache for each partition and sorts each partition separately.

If you do not configure the cache size to sort all of the data in memory, a warning appears in the session log, stating that the Integration Service made multiple passes on the source data. The Integration Service makes multiple passes on the data when it has to page information to disk to complete the sort. The message specifies the number of bytes required for a single pass, which is when the Integration Service reads the data once and performs the sort in memory without paging to disk. To increase session performance, configure the cache size so that the Integration Service makes one pass on the data.