02.Redis Key

• Redis key is:

  • a unique identifier (string) that points to a value in Redis.
  • Redis is best thought of as: key -> typed value (string/hash/list/set/zset/stream…).

• The key naming pattern

  • Standard format namespace:entity:id[:subtype][:dimension...]
    • Example
      • qa:v1:{docId}:{questionHash}, user:{userId}:session ,rank:doc:{docId}
    • Rules
      • Use namespaces (qa:, user:, rank:, idx:, ratelimit:, lock:).
      • Use colons : to separate segments.
      • Put high-cardinality parts last (hash/uuid/timestamp).
      • Don’t put raw user input in keys → normalize + hash.
      • Add a version when logic may change (v1, v2).

• Keys and data types (type safety)

  • A key has one type forever until deleted.

• TTL and expiration

  • TTL controls how long a key lives.

• Delete keys safely

  • use iterative
    • SCAN 0 MATCH qa:* COUNT 1000 (iterative, safer)

• Key design for your Doc QA cache