Always wrap multiple related database operations in a transaction to ensure data consistency and prevent partial updates. This applies to operations across different tables or when coordinating database updates with external services (e.g., Redis cache). Example: ```diff - const dbPromise = prisma.label.upsert({ ... }) - const redisPromise = saveUserLabel({ ... }) - await Promise.all([dbPromise, redisPromise]) + await prisma.$transaction(async (tx) => { + const dbResult = await tx.label.upsert({ ... }); + await saveUserLabel({ ... }); + }); ``` Key benefits: - Ensures all operations succeed or fail together - Prevents inconsistent state between related data - Maintains referential integrity - Simplifies error handling and rollbacks Apply this pattern when: - Updating multiple related records - Coordinating DB changes with cache updates - Performing data migrations or merges - Managing cross-service data consistency