During a mapping run, the Data Integration Service caches input data until it can perform the rank calculations.

The Rank transformation differs from the transformation functions MAX and MIN. The Rank transformation returns a group of top or bottom values, not just one value. For example, use a Rank transformation to select the top 10 salespersons in a given territory. Or, to generate a financial report, you might use a Rank transformation to identify the three departments with the lowest expenses in salaries and overhead. While the SQL language provides many functions designed to handle groups of data, identifying top or bottom strata within a set of rows is not possible using standard SQL functions.

You connect all ports representing the same row set to the transformation. The rows that fall within that rank, based on some measure you set when you configure the transformation, pass through the Rank transformation.

As an active transformation, the Rank transformation might change the number of rows passed through it. You might pass 100 rows to the Rank transformation, but select to rank only the top 10 rows. The top 10 rows pass from the Rank transformation to another transformation.

You can connect ports from one transformation to the Rank transformation. You can also create local variables and write non-aggregate expressions.