Reviewed by Aditya Kumar · Last reviewed 2026-03-24
**Nulls**: COALESCE(col, default); IS NULL checks; avoid NULL in NOT IN. **Duplicates**: ROW_NUMBER() OVER (PARTITION BY key ORDER BY ts DESC) keep rn=1; or GROUP BY with aggregations. **Timestamps**: Parse to ISO 8601; TRY_CAST or regex; store UTC. **Pipeline**: Validation...
Nulls: COALESCE(col, default); IS NULL checks; avoid NULL in NOT IN. Duplicates: ROW_NUMBER() OVER (PARTITION BY key ORDER BY ts DESC) keep rn=1; or GROUP BY with aggregations. Timestamps: Parse to ISO 8601; TRY_CAST or regex; store UTC. Pipeline: Validation layer → quarantine failures → log for remediation. Data contract: Schema registry; reject on violation.
Red Flag: Silently dropping nulls without logging. Pro-Move: 'We use Great Expectations: null check, uniqueness, timestamp format—failures go to quarantine with error_code; we alert on >1% failure rate.'
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