What Most CSV Ingestion Scripts Get Wrong (And How to Fix It)

Most CSV ingestion scripts are written in 30 minutes. Most ingestion failures take 3 months to notice. The problem isn’t CSV. The problem is missing guarantees. In small teams, CSV ingestion often looks like this: Read file Loop rows Insert into database Print “Done” It works. Until the export format changes. Until the file is empty. Until duplicates accumulate. Until a partial insert corrupts reporting. Here’s what most ingestion scripts get wrong. 1. They Don’t Validate Structure Explicitly Many scripts assume the column order never changes. That assumption eventually breaks. Instead of trusting positional mapping, validate headers explicitly: EXPECTED_HEADERS = [ "date", "customer_id", "amount", "currency", "status" ] if headers != EXPECTED_HEADERS: raise ValueError("Schema mismatch detected") Order-sensitive comparison is intentional. If upstream changes, ingestion should stop immediately. Silent drift is worse than a crash. 2. They Don’t Sanity-Check Volume An empty CSV import sho