You can debug a valid mapping to gain troubleshooting information about data and error conditions. To debug a mapping, you configure and run the Debugger from within the Mapping Designer. The Debugger uses a session to run the mapping on the Integration Service. When you run the Debugger, it pauses at breakpoints and you can view and edit transformation output data.
You might want to run the Debugger in the following situations:
Before you run a session.
After you save a mapping, you can run some initial tests with a debug session before you create and configure a session in the Workflow Manager.
After you run a session.
If a session fails or if you receive unexpected results in the target, you can run the Debugger against the session. You might also want to run the Debugger against a session if you want to debug the mapping using the configured session properties.