Core

Idempotent Data Pipelines: Reruns Without Duplicate Rows

How to make a pipeline safe to rerun: insert-overwrite by partition, MERGE keyed on a business id, and deterministic transforms instead of blind appends.

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RELATED CONCEPTS

Idempotency and Exactly-Once Effects Change Data Capture Data Quality and Contracts Window Functions

PRACTICE THIS IN REAL QUESTIONS

SQL & Data EngineeringSCD Type 2 in Delta Lake: track history with one atomic MERGE.→SQL & Data EngineeringDesign a data pipeline that is safe to re-run: idempotent writes, late data, and exactly-once effects.→SQL & Data EngineeringGiven rows with start and end timestamps, merge all overlapping intervals per user in SQL.→SQL & Data EngineeringYou shipped a logic bug three months ago. How do you safely backfill and reprocess the affected data?→SQL & Data EngineeringGroup a stream of user events into sessions in SQL (30-minute inactivity gap) using window functions.→SQL & Data EngineeringTop-N per group in SQL: ROW_NUMBER vs RANK vs DENSE_RANK.→

COMPANIES THAT ASSUME THIS

Scale AI Palantir Databricks Snowflake Zendesk Clay

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