ETL/ELT Pipelines Node.js Streaming ETL Batch Writer Python (Polars — recommended for performance) Apache Airflow DAG Database-Native ELT Anti-Patterns | Anti-Pattern | Fix | |--------------|-----| | Loading all data into memory | Use streaming (Node.js streams, generators) | | No idempotency (re-runs duplicate data) | Use upserts or dedup before insert | | No error handling per record | Log bad records, continue processing good ones | | No data validation | Validate schema and types before loading | | Monolithic ETL script | Split into extract, transform, load stages | Production Checklist -…