fete/specs/013-auto-delete-expired/research.md

Research: Auto-Delete Expired Events

Feature: 013-auto-delete-expired | Date: 2026-03-09

Deletion Strategy

• Decision: Direct native SQL DELETE query via Spring Data JPA @Query.
• Rationale: Simplest approach. No entity loading overhead. The existing ON DELETE CASCADE FK constraint on fk_rsvps_event_id (migration 003-create-rsvps-table.xml) handles cascading deletion of RSVPs automatically. The existing idx_events_expiry_date index ensures the WHERE clause is efficient.
• Alternatives considered:
  • JPA repository deleteAll(findExpired()): Loads entities into memory first, unnecessary overhead.
  • Database-level cron (pg_cron): Less portable, adds external dependency.
  • Soft delete with lazy cleanup: Over-engineered for fete's scale and privacy goals.
  • No deletion (filter only): Contradicts privacy-by-design principle.

Scheduling Mechanism

• Decision: Spring @Scheduled(cron = ...) annotation.
• Rationale: Already available in Spring Boot, no additional dependencies. Simple, declarative, well-tested.
• Alternatives considered:
  • Quartz Scheduler: Too heavy for a single daily job.
  • External cron (OS-level): Requires separate process management, harder to test.

Transaction Behavior

• Decision: Single transaction for the DELETE statement.
• Rationale: A single DELETE FROM events WHERE expiry_date < CURRENT_DATE is atomic. If the DB connection drops mid-execution, the transaction rolls back and no events are partially deleted. The next run picks up all expired events.

Enabling @Scheduled

• Decision: Add @EnableScheduling to FeteApplication.java.
• Rationale: Simplest approach. Only one scheduled job exists, no need for a separate config class.