PostgreSQL's case_not_found: Why Your Stored Procedures Fail in Production

Error 20000 can silently break production when business requirements evolve, making it a critical risk for database-driven applications. Unlike standard SQL CASE expressions, PL/pgSQL CASE statements demand explicit handling of all possible inputs, requiring developers to anticipate new data values and NULL cases. Mastering the three main causes—missing ELSE clauses, unhandled data changes, and NULL value gaps—is essential for writing production-safe stored procedures.