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keyboard_arrow_down Operators, Hooks, and Sensors
Data Engineering Path  ·  Airflow
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Theoretical Quiz — Module 3

📝 Test Your Knowledge

Q1. What is the difference between an Operator, a Sensor, and a Hook?

Show Answer
  • Operator: Defines and executes a task action (run Python, execute SQL, submit Spark job)
  • Sensor: A special operator that waits for a condition (file exists, API is ready)
  • Hook: A low-level connection interface used by operators internally to connect to external systems

Q2. Explain the three sensor modes (poke, reschedule, deferrable) and when to use each.

Show Answer
  • poke: Holds a worker slot continuously. Use for short waits (< 5 min)
  • reschedule: Releases worker between poke attempts. Use for medium waits (5-60 min)
  • deferrable: Fully async via Triggerer. Use for long waits (hours). Most resource-efficient

Q3. Why should you use Airflow Connections instead of hardcoding credentials?

Show Answer
  1. Security: Connections are encrypted in the metadata database
  2. Reusability: Multiple DAGs can share the same connection
  3. Environment separation: Different connection IDs for dev/staging/prod
  4. No code changes: Update credentials in the UI without redeploying DAGs
  5. Audit trail: Connection access is logged
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