What do you mean to "fail all data"? to stop the process?
you can use event script to stop the process if anything you specify happens.
Yes, if any mapping is missing and autocorrect is not enabled, I want to batch loader to not push any data to my SQL schema since I want to do an append instead of replace and do not want duplications.
Validation of mapping happens in validate phase but batch loader pushes the data to my SQL during import phase. Is this correct? If so, then how can I ensure that the data that got loaded to SQL during import phase will get deleted if any mapping error occurs during Validate phase?