Unlock 16 Powerful Redis Patterns for Scalable Backend Systems

1. Caching

String type

Examples: hot data cache (e.g., reports, celebrity scandals), object cache, full-page cache, which can improve hot data access.

2. Distributed Data Sharing

String type, because Redis is a distributed independent service that can be shared among 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 when 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, using atomicity.

incrby userid 1000

Used in sharding scenarios to obtain a block of IDs at once.

5. Counter

int type, incr method.

Examples: article view count, microblog likes; can tolerate some delay by writing to Redis first and syncing to DB later.

6. Rate Limiting

int type, incr method.

Use visitor IP and other info as key; increment on each request, return false when limit exceeded.

7. Bit Statistics

String type bitcount (bitmap data structure 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 the bits of 'a' (ASCII 97 = 01100001) */

Examples: online user statistics, retention statistics.

setbit onlineusers 01
setbit onlineusers 11
setbit onlineusers 20

Supports bitwise AND, OR, XOR, NOT operations.

BITOP AND destkey key1 key2 ...
BITOP OR destkey key1 key2 ...
BITOP XOR destkey key1 key2 ...
BITOP NOT destkey key

Calculate users online for 7 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 strings are also possible on hashes.

Key: user ID; field: product ID; value: quantity. Increment with hincr, decrement with hdecr, delete with hdel, get all with hgetall, count fields with 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 and brpop, with optional timeout.

blpop key timeout – removes and returns the first element, blocking until an element is available or timeout.

brpop key timeout – removes and returns the last element, with similar blocking behavior.

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

11. Lottery

Redis provides a random value retrieval.

spop myset

12. Likes, Check‑in, Clock‑in

Assume a microblog ID t1001 and user ID u3001.

Use key like:t1001 to store all users who liked the post.

Like a post: sadd like:t1001 u3001

Cancel like: srem like:t1001 u3001

Check if liked: sismember like:t1001 u3001

All users who liked: smembers like:t1001

Like count: scard like:t1001

13. Product Tags

Maintain tags for a product with key tags:i5001.

sadd tags:i5001 "clear display"
sadd tags:i5001 "true color screen"
sadd tags:i5001 "extremely smooth workflow"

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, and LCD:

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

15. User Follow & Recommendation Model

follow for following, fans for followers.

Mutual follow:

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

People I follow also follow them (intersection): sinter 1:follow 2:fans Potential acquaintances:

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