DEA-C01 Practice Question 23: S3 EventBridge Arrival Trigger
AWS Certified Data Engineer – Associate (DEA-C01) · Test 3 · question 3 of 10
Partners upload CSV files to a single Amazon S3 prefix at unpredictable times, sometimes six files in an hour, sometimes none all afternoon. An hourly scheduled AWS Glue job processes whatever has arrived. The team is unhappy on two counts: files can sit unprocessed for almost an hour, and the job still starts (and bills) on hours when nothing arrived.
Which change processes each file shortly after it arrives with the least operational overhead?
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Answer:
Amazon S3 "can send events to Amazon EventBridge whenever certain events happen in your bucket." Once EventBridge is enabled on the bucket, S3 emits an Object Created event for every new object, and an EventBridge rule can filter on the prefix and route the event to a target. Processing then starts seconds after an upload, and nothing runs at all on quiet hours. This is configuration only, a bucket setting and a rule, so the operational overhead is close to zero.
Option B shrinks the delay but does not remove it, and it makes the second complaint much worse: a five-minute schedule fires 288 times a day, the large majority of them finding nothing to do and still incurring Glue job startup and billing.
Option C reinvents S3 event notifications in application code, and badly. It needs somewhere to persist the previous listing, it must handle paginated listings of a growing prefix, it still has up to a minute of latency, and every polling invocation costs LIST requests whether or not anything arrived.
Option D uses a reporting feature as a trigger. S3 Inventory is delivered on a daily or weekly schedule, so the freshness would be far worse than today's hourly job, not better.
Reference: Using EventBridge with Amazon S3