AWS Certified Data Engineer Associate DEA-C01 Practice Question

AWS Glue job bookmarks record the state of the input data that a job has already processed. When bookmarks are enabled, the job automatically skips files it has successfully loaded in earlier runs, preventing the same records from being appended twice. Overwrite mode could remove duplicates but risks data loss if the job fails midway and is less efficient. Deleting landing files with a lifecycle rule still lets duplicates through if the job re-reads already copied data before deletion, and it provides no guard against partial reruns. Adding a Step Functions task to run an Athena DELETE query introduces extra cost and complexity and only corrects duplicates after they occur rather than preventing them.