reviewing-oracle-to-postgres-migration

Reviewing Oracle-to-PostgreSQL Migration is a review and risk-assessment skill that surfaces migration hazards by cross-referencing code against a curated library of documented Oracle/PostgreSQL behavioral differences. It solves a costly, error-prone problem: subtle semantic gaps between the two databases (empty-string-as-NULL, refcursor handling, type coercion, default collations and sorting, UNION ALL planner risks, materialized-view refresh requirements, timestamp/timezone behavior, no-data-found exceptions, and concurrent-transaction differences) that pass code review but break in production.

The skill offers two workflows. The planning/risk-assessment workflow identifies migration scope (procedures, triggers, queries, views, and the app code that calls them), screens each documented insight in references/REFERENCE.md for applicability, and documents risks with recommended fix patterns, flagging insights that require a design decision. The validation workflow maps a completed migration artifact, cross-checks each applicable insight, verifies integration-test coverage for both happy-path and failure scenarios, and gates the result with a checklist asserting every applicable insight was addressed, scripts run, and tests pass. Each concern has a dedicated reference file with problem descriptions, root causes, recommended SQL/collation patterns (for example CAST(... AS TEXT) instead of TO_CHAR on numerics, or wrapping DISTINCT queries before ordering with an explicit collation), migration checklists, and error messages to watch for.

It targets database engineers, backend developers, and reviewers planning or validating Oracle-to-PostgreSQL migrations, especially those wanting to ensure integration tests actually cover the semantic differences. It is read-only advisory guidance; it does not execute migrations.