Redis Persistence and Internals: RDB/AOF, Data Structures, and Advanced Mechanisms

Persistence and internals are centered on RDB/AOF, data structures, and expiration strategies in Redis持久化.md (Redis Persistence), 原理篇.md (Internals) (56KB), and RedisPersistence.md. This page emphasizes recoverability and performance trade-offs.

Core Mechanism

• RDB: periodic snapshots, fast recovery, high fork cost with large datasets, may lose recent writes.
• AOF: appends commands, three fsync modes everysec/always/no, rewrite compaction; safer but slower replay.
• The internals article further covers SDS, Dict, ZipList/ListPack, QuickList and other underlying structures, plus expiration, eviction (LRU/LFU), and master-replica replication.

Applicability

• Tolerate small data loss and want fast recovery → RDB.
• Want minimal loss → AOF (or hybrid persistence).

Not Applicable and Risks

• AOF always amplifies latency under write-heavy workloads; rewrite fork/IO during the period must be evaluated.
• The internals article version is not pinned (Heima course version) and may drift from the production Redis version.

Minimum Verification

1. Enable RDB and AOF separately, kill and restart, compare recovered data and time.
2. Load-test during BGREWRITEAOF and observe latency and fork.

Evidence and Uncertainty

• Source facts: ingest-redis-persistence captures 3 source notes verbatim; the internals article has not been version-pinned.
• Synthesis: This page turns the snapshot vs append-log trade-off into a selection table.
• Unconfirmed: Specific Redis versions, hybrid persistence switches, and underlying structures differ across versions.

Related Pages

• redis-business-patterns
• redis-heima-practice
• database-schema-drift

Sources and related documents

• ingest-redis-persistence
• Redis Business Patterns: Caching, Distributed Locks, Message Queues, Feed Streams, and Flash Sales
• Redis Heima Practice: Distributed Cache, Multi-Level Cache, and Best Practices
• Database Schema Drift: Locating with the history, schema, and query Views