Hashes

#lecture #redis #data-structure #keys

1. Hash

• Key with named fields
• Single level
• Provide commands on those fields
  • e.g.) INCR
• Dynamically add and remove fields
• Stored extremply efficiently
• Are not recursive

2. HSET - 해시 저장

HSET Syntax

HSET key field value [field value ...]

• 해시를 저장한다.

HSET example

HSET evnet:judo capacity 12000 location "Nippo Budokan" ticket_price:gold 100 availability:gold 8000

HSET with REDISINSIGHT

3. HEXISTS, HDEL, HINCRBY, HINCRBYFLOAT

HEXISTS - 필드의 여부를 확인

> HEXISTS event:judo capacity 
(integer) 1
> HEXISTS event:judo timezone
(nil)

> HINCRBY event:judo availability:gold -10 
(integer) 7990

4. HGET, HGETALL, HSCAN, HMGET, HKEYS, HVALS

이런 해시 값에서 HSCAN 을 이용해 모든 availiablity:* 패턴의 field 를 순회해보자.

> HSCAN event:judo 0 match availability:* 
1) "0" 
2) 1) "availability:gold" 
   2) "7990" 
   3) "availability:silver" 
   4) "2000"

5. Hash Uses Cases

• Rate Limiting
• Session Cache

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Last update: May 16, 2023
Created: May 16, 2023