Compare RDB and AOF. When would you use RDB+AOF together?

RDB: point-in-time snapshots, compact, fast restarts, but data loss between snapshots AOF: logs every write, durable (fsync policies: always, everysec, no), larger files, slower restart Both together: AOF is used on restart (more complete), RDB for backups/fast forks. With aof-use-rdb-preamble yes (default in Redis 4+), AOF starts with an RDB snapshot for fast loads.