Clicking on the 'Map Columns' button in the comparison options screen shows the comparison mapping & filter screen
Here we can select the source and target objects (using the top two drop-downs) and select the index that will be used to walk to comparison. We can enable or disable comparisons of a particular column by ticking or un-ticking the tick box to the left of the column row. We can also change the source and target columns by changing the drop downs in a column row. The color of the column row changes to indicate the status of the column:
A green column row is matched, a red column row is unmatched. A yellow column row forms part of the comparison key, and a gray column row is not selected for comparison. By clicking the filter button at the top of the dialog on either the source or target, the edit filter dialog is shown:
In this dialog we simply enter the WHERE clause for the relevant storage object. To remove the filter click on the 'Clear' button. When a filter is active for the source or target, the filter icon is gold. To return to the comparison options screen, click OK or Cancel on the edit mappings dialog.