Unlock 16 Powerful Redis Patterns for Scalable Backend Systems

1. Cache

String type caches hot data such as reports or popular items, object cache, full-page cache, improving access speed for hot data.

2. Distributed Data Sharing

String type; Redis is a distributed independent service that can be shared across multiple applications, e.g., distributed session.

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

3. Distributed Lock

String type setnx method acquires lock only if 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

Integer type using incrby for atomic increment, e.g., incrby userid 1000 to allocate a range of IDs for sharding.

5. Counter

Integer type using incr method, e.g., article view count, likes, allowing slight delay by writing to Redis then syncing to DB.

6. Rate Limiting

Integer type using incr; key composed of visitor IP and other info, increment on each request, return false when limit exceeded.

7. Bit Statistics

String type bitcount (bitmap) stores characters as 8‑bit binary, useful for massive statistics.

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

Examples: online user statistics, retention.

setbit onlineusers 01
setbit onlineusers 11
setbit onlineusers 20

Supports bitwise AND, OR, XOR, NOT.

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

Calculate users online all 7 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; any operation possible on strings can be done on hashes.

key: user id; field: product id; value: quantity.

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

9. User Timeline

List (doubly linked list) used as timeline, ordered insertion.

10. Message Queue

List provides blocking pop operations blpop/brpop with timeout.

blpop key timeout – removes and returns first element, blocks if empty.

brpop key timeout – removes and returns last element, blocks if empty.

These correspond to Java blocking queue semantics: queue (FIFO) with rpush + blpop, stack (LIFO) with rpush + brpop.

11. Lottery

Random selection using set pop.

spop myset

12. Likes, Check‑in, Clock‑in

Assuming a post ID t1001 and user ID u3001, use like:t1001 to store all users who liked the post.

sadd like:t1001 u3001 – like

srem like:t1001 u3001 – unlike

sismember like:t1001 u3001 – check like

smembers like:t1001 – list all likers

scard like:t1001 – count likes

This is simpler than using a relational database.

13. Product Tags

Maintain tags with tags:i5001 set.

sadd tags:i5001 "clear picture"

sadd tags:i5001 "vivid color display"

sadd tags:i5001 "smooth workflow"

14. Product Filtering

// difference
sdiff set1 set2
// intersection
sinter set1 set2
// 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:

sadd 1:follow 2

sadd 2:fans 1

sadd 1:fans 2

sadd 2:follow 1

Find people I follow who also follow me (intersection):

sinter 1:follow 2:fans

Potential acquaintances (difference):

sdiff 2:follow 1:follow – for user1

sdiff 1:follow 2:follow – for user2

16. Ranking

Increment news click count:

zincrby hotNews:20190926 1 n6001

Get top 15 items today:

zrevrange hotNews:20190926 0 15 withscores