This is a cut and paste from power center help... ****************************** example using a dynamic lookup cache you can use a dynamic lookup cache when you need to insert and update rows in your target. When you use a dynamic lookup cache, you can insert and update the cache with the same data you pass to the target to insert and update. For example, you can use a dynamic lookup cache to update a table that contains customer data. Your source data contains rows that you need to insert into the target and rows you need to update in the target. The lookup transformation uses a dynamic lookup cache. When the session starts, the powercenter server builds the lookup cache from the target table. When the powercenter server reads a row that is not in the lookup cache, it inserts the row in the cache and then passes the row out of the lookup transformation. The router transformation directs the row to the upd_insert_new update strategy transformation. The update strategy transformation marks the row as insert before passing it to the target. The target table changes as the session runs, and the powercenter server inserts new rows and updates existing rows in the lookup cache. The powercenter server keeps the lookup cache and target table synchronized. To generate keys for the target, use sequence-id in the associated port. The sequence id generates primary keys for new rows the powercenter server inserts into the target table. without the dynamic lookup cache, you need to use two lookup transformations in your mapping. Use the first lookup transformation to insert rows in the target. Use the second lookup transformation to recache the target table and update rows in the target table. ************************* can someone explain me how two lookup can replace the dynamic cache (last paragraph)? assume source data is as follows cust id cust name cust location c001 xyz pasadena c002 abc glendale c001 xyz burbank regards, -robert