Why Database NULL Values Destroy Query Performance

Episode 45 of Database Tech with Fexingo digs into a silent performance killer: how NULL values in your database columns can lead to full table scans, bloated indexes, and query plans that ignore your best indexes. Lucas and Luna walk through a real-world example from an e-commerce order database, showing how three-valued logic (TRUE, FALSE, UNKNOWN) confuses the query optimizer. They explain why 'WHERE amount > 100' might not return rows with NULL amounts, why indexes on nullable columns can be partially useless, and how NOT IN subqueries with NULLs can return zero rows even when data exists. They cover concrete fixes: using NOT NULL constraints, COALESCE defaults, filtered indexes, and IS NULL predicates. No theory without practice — this episode gives you one actionable tip: add a NOT NULL constraint to every column that should never be empty, and watch your query times drop. #DatabasePerformance #NULLValues #QueryOptimization #SQL #DatabaseIndexing #ThreeValuedLogic #DatabaseTips #TechPodcast #DataEngineering #DatabaseDesign #SQLPerformance #IndexTuning #DatabaseMistakes #Technology #FexingoBusiness #BusinessPodcast #DatabaseTech #LucasAndLuna Keep every episode free: buymeacoffee.com/fexingo