Shared database

Intent

Multiple services access the same database/schema directly.

Use when

• Transitional state during migration, or when organizational/operational constraints require it temporarily.

Avoid / watch-outs

• Shared schemas create tight coupling and make independent deployment/versioning difficult.
• Schema changes become cross-team coordination events; failure domains widen.

Skill mapping

• architecture: treat as a migration phase; define an exit strategy toward owned schemas (Database per service).
• spec: make coupling explicit and document compatibility rules for schema changes.
• testing: add characterization tests to catch accidental breaking schema changes.