AWS Certified Data Engineer Associate DEA-C01 Practice Question

AWS Glue provides four trigger types: scheduled, conditional, on-demand, and event-based. A scheduled trigger can launch a crawler or job on a cron-based schedule. For example, the cron expression cron(0 1 * * ? *) runs every day at 01:00 UTC. A conditional trigger can start one or more crawlers or jobs after specified predecessors reach a designated state, such as a crawler's SUCCEEDED state. Creating a scheduled trigger that starts the crawler at 01:00 UTC and a conditional trigger that fires when the crawler succeeds and launches the ETL job keeps the solution entirely within AWS Glue and guarantees that the job never starts until the crawler completes.

Using EventBridge rules or Step Functions introduces additional services, violating the constraint. Scheduling only the job and invoking the crawler from within the job is unreliable because the crawler runs asynchronously and the job cannot natively block until the crawl finishes.