Reviewed by Aditya Kumar · Last reviewed 2026-03-24
**Strategy**: (1) Validate at source—schema registry, API validation; (2) Stream validation—Flink/Spark checks (nulls, types, ranges); (3) DLQ—quarantine invalid for triage; (4) Monitoring—alert on DLQ growth; (5) Reprocess from DLQ after fix. Don't block stream; use...
Pro-Move: 'Flink job with side-output for bad records. DLQ to S3; daily report. Reprocess job after schema fix. <0.01% to DLQ.'
Strategy: (1) Validate at source—schema registry, API validation; (2) Stream validation—Flink/Spark checks (nulls, types, ranges); (3) DLQ—quarantine invalid for triage; (4) Monitoring—alert on DLQ growth; (5) Reprocess from DLQ after fix. Don't block stream; use side-outputs; fail fast. Goldman: quality critical for trading.
Pro-Move: 'Flink job with side-output for bad records. DLQ to S3; daily report. Reprocess job after schema fix. <0.01% to DLQ.'
According to DataEngPrep.tech, this is one of the most frequently asked System Design/Architecture interview questions, reported at 1 company. DataEngPrep.tech maintains an editor-reviewed database of 1,863 data engineering interview questions across 7 categories.