Fingerprint vs. Text Diff: How to Gate Agent-Written SQL in CI

A debate in software engineering circles is examining the best way to regression-test SQL queries written by AI agents, where two main approaches compete: query fingerprinting and literal text diffs. Fingerprinting strips formatting and aliases to compare a normalized digest, catching structural changes while ignoring harmless restyles — a strength on high-churn reporting queries. Literal text diffs, by contrast, flag every changed character, making them better suited for privileged DML and security-sensitive paths where exact values like status strings matter. Each method has blind spots: fingerprints can miss unbounded date literals, while text diffs generate noise when agents reformat identical logic differently. The article argues that neither approach alone is sufficient, and that teams need a deliberate decision rule combining both gates to avoid false failures and silent plan drift.