Release and Upgrade Rules

This directory collects release-policy and upgrade-safety rules consolidated from the former doc/developer.md and the developer wiki. Use it when a patch changes SQL API, C API, extension upgrade behavior, dependency requirements, or supported PostgreSQL versions.

• API compatibility indexes SQL/C API compatibility rules.
• Versioning policy explains version terminology, library naming, and release-line compatibility constraints.
• Deprecating and removing API explains SQL-visible object removals and C API stubs for pg_upgrade.
• SQL upgrade and deprecation explains Availability:, Changed:, Replaces, before/after upgrade hooks, and parser-sensitive SQL style.
• Dependency and support guards explains dependency-version guards and the checklist for dropping PostgreSQL support.
• Testing and debugging explains sandboxed regression roles used by CI and downstream builders.

• Do not add SQL API functions in a patch release.
• Do not remove SQL API or C API functions except in a major release unless the old signatures are safely stubbed or migrated.
• Do not require newer dependency-library versions in a micro release.
• Treat pg_upgrade as the design constraint for legacy SQL and C signatures.
• Keep upgrade metadata comments current and minimal.