Instruction file imported from Archasion/eventra (.github/instructions/database.instructions.md). Copyright stays with the author.

Database Code Review Instructions

Review database changes for invariant enforcement, transactional safety, migrations, and tenant isolation.

• PostgreSQL is the authoritative source for transactional business state.
• Prefer database constraints for invariants that can be enforced structurally.
• Do not rely solely on application checks for uniqueness or ownership constraints that must hold under concurrency.
• Check read-then-write patterns for race conditions.
• Ensure related writes that must succeed or fail together share the same database transaction.
• Avoid accidentally performing transaction-sensitive queries outside the transaction handle.
• Review indexes for queries introduced on frequently filtered, joined, or uniqueness-sensitive fields.
• Check foreign-key behavior and deletion semantics intentionally.
• Tenant-owned rows must not be queryable across organisations due to missing ownership predicates.
• Never use Typesense or Redis state to determine authoritative inventory, order, payment, or ticket outcomes.
• Monetary values must not use floating-point database types when exact arithmetic is required.
• Immutable transaction snapshots such as purchased prices must not later depend on mutable event pricing records.
• Migration changes must be reproducible and versioned.
• Review destructive migrations for data-loss risk.
• Avoid silently changing existing column semantics without a migration strategy.
• Concurrency-sensitive database behavior requires integration tests against real PostgreSQL rather than mocked repositories.