Beyond Caching: 16 Powerful Redis Use Cases

1. Caching

String type. Example: hot data cache (e.g., reports, trending topics), object cache, full-page cache, which can improve access to hot data.

2. Distributed Data Sharing

String type. Because Redis is a distributed independent service, it can be shared across multiple applications.

Example: distributed Session.

<dependency>
  <groupId>org.springframework.session</groupId>
  <artifactId>spring-session-data-redis</artifactId>
</dependency>

3. Distributed Lock

String type setnx method, succeeds only if the key does not exist, returns true.

public static boolean getLock(String key) {
    Long flag = jedis.setnx(key, "1");
    if (flag == 1) {
        jedis.expire(key, 10);
    }
    return flag == 1;
}
public static void releaseLock(String key) {
    jedis.del(key);
}

4. Global ID

int type, incrby, utilizes atomicity. incrby userid 1000 Useful in sharding scenarios to obtain a range of IDs at once.

5. Counter

int type, incr method.

Examples: article view count, tweet likes; can tolerate some delay by writing to Redis first then synchronizing to the database.

6. Rate Limiting

int type, incr method.

Use visitor IP and other information as the key; each access increments the count, and exceeding the limit returns false.

7. Bit Statistics

String type bitcount (bitmap introduced in Redis 1.6.6).

Characters are stored as 8‑bit binary.

set k1 a
setbit k1 6 1
setbit k1 7 0
get k1
/* 6 7 represent bits of 'a' (ASCII 97) -> 01100001 */

Applications: online user statistics, retention statistics.

setbit onlineusers 01
setbit onlineusers 11
setbit onlineusers 20

Supports bitwise AND, OR, XOR, NOT.

BITOPAND destkey key [key ...]
BITOPOR destkey key [key ...]
BITOPXOR destkey key [key ...]
BITOPNOT destkey key

Calculate users online for seven consecutive days:

BITOP "AND" "7_days_both_online_users" "day_1_online_users" "day_2_online_users" ... "day_7_online_users"

8. Shopping Cart

String or hash. All operations possible on String are also possible on hash.

Data structure: key = user id; field = product id; value = quantity.

+1: hincr; -1: hdecr; delete: hdel; all: hgetall; count: hlen.

9. User Timeline

list, a doubly linked list, can be used directly as a timeline; insertion keeps order.

10. Message Queue

List provides two blocking pop operations: blpop/brpop with timeout.

blpop key1 timeout – removes and returns the first element, blocks if the list is empty.

brpop key1 timeout – removes and returns the last element, blocks if the list is empty.

These correspond to Java’s blocking queue. Queue (FIFO): rpush + blpop. Stack (LIFO): rpush + brpop.

11. Lottery

Random value retrieval.

spop myset

12. Likes, Check‑in, Clock‑in

Assume tweet ID t1001 and user ID u3001. Use the set like:t1001 to maintain all users who liked the tweet.

sadd like:t1001 u3001 – like

srem like:t1001 u3001 – unlike

sismember like:t1001 u3001 – check if liked

smembers like:t1001 – all users who liked

scard like:t1001 – count of likes

This is simpler than using a relational database.

13. Product Tags

Use tags:i5001 to maintain all tags of a product.

sadd tags:i5001 "画面清晰细腻"

sadd tags:i5001 "真彩清晰显示屏"

sadd tags:i5001 "流程至极"

14. Product Filtering

// Get difference
sdiff set1 set2
// Get intersection
sinter set1 set2
// Get union
sunion set1 set2

Example: iPhone11 released.

sadd brand:apple iPhone11
sadd brand:ios iPhone11
sad screensize:6.0-6.24 iPhone11
sad screentype:lcd iPhone11

Filter products that are Apple, iOS, screen size 6.0‑6.24, LCD.

sinter brand:apple brand:ios screensize:6.0-6.24 screentype:lcd

15. User Follow & Recommendation Model

follow – following, fans – followers.

Mutual follow (intersection):

sadd 1:follow 2
sadd 2:fans 1
sadd 1:fans 2
sadd 2:follow 1

People I follow also follow him (intersection): sinter 1:follow 2:fans Possible acquaintances (difference):

sdiff 2:follow 1:follow   // for user 1
sdiff 1:follow 2:follow   // for user 2

16. Ranking

Increment news click count: zincrby hotNews:20190926 1 n6001 Get top 15 items today:

zrevrange hotNews:20190926 0 15 withscores