Debugging DataSources in SAP ECC
You can debug DataSources by using the Debug Mode in the Extractor Checker (RSA3).
If you need to use the ABAP debugger or you just want to see the underlying ABAP code, you can switch to Debug Mode. You use ABAP debugging to break down the program into its atomic level, basically one record at a time.
For more information, go to https://wiki.scn.sap.com/wiki/display/ABAP/ABAP+Debugger.