**XCom**: Cross-communication—tasks pass small data (e.g., file path, ID). Push via return value or xcom_push(); pull via xcom_pull(). Stored in metadata DB. **Limitation**: Not for large data—metadata DB is not a store. Typical limit ~1 KB per value (configurable but not...
This easy-level Cloud/Tools question appears frequently in data engineering interviews at companies like Tech Mahindra. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (airflow) will help you answer variations of this question confidently.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
XCom: Cross-communication—tasks pass small data (e.g., file path, ID). Push via return value or xcom_push(); pull via xcom_pull(). Stored in metadata DB. Limitation: Not for large data—metadata DB is not a store. Typical limit ~1 KB per value (configurable but not recommended to increase). Use: Pass S3 paths, query IDs, status codes. Best practice: Pass references, not payloads. For large data, use external storage (S3, DB) and pass reference. Scalability: Many XComs add DB load; keep minimal.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked Cloud/Tools interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.