Using Merge rows (diff) on the Pentaho engine

If you are running your transformation on the Pentaho engine, use the following instructions to set up the Merge rows (diff) step.

Important: When using the Pentaho transformation engine, the reference rows and compare rows must be sorted on the specified keys. When using the Merge rows (diff) step within a PDI transformation, such as with the Sort rows step, sorting works correctly. However, if the data is sorted outside of PDI, such as in a SQL query, you may run into issues with the internal case sensitive/insensitive flag or other collations. If you are using the Merge rows (diff) step with the Spark engine, see Using Merge rows (diff) on the Spark engine.