Redis is a powerful in-memory data store that can function as a database, cache, and message broker. Its versatile data structures and commands make it an essential tool for developers looking to build high-performance applications. In this blog, we will delve into the core data types and commands in Redis, with a focus on practical use cases and code examples using ioredis for Node.js.

1. Strings

Strings are the simplest data type in Redis. They are binary-safe and can hold any data, such as text or serialized JSON.

• • SET: Stores a string value.
    

Copy
1await client.set('key', 'value');

• • SETNX: Stores a string value only if the key doesn’t already exist, useful for implementing locks.

Copy
1await client.setnx('key', 'value');

• • GET: Retrieves a string value.

Copy
1const value = await client.get('key');

• • MGET: Retrieves multiple string values in a single operation.

Copy
1const values = await client.mget('key1', 'key2');

2. Lists

Redis lists are linked lists of string values. They are frequently used to implement stacks and queues.

• • LPUSH: Adds a new element to the head of a list.

Copy
1await client.lpush('list', 'value');

• • RPUSH: Adds a new element to the tail of a list.

Copy
1await client.rpush('list', 'value');

• • LPOP: Removes and returns an element from the head of a list.

Copy
1const value = await client.lpop('list');

• • RPOP: Removes and returns an element from the tail of a list.

Copy
1const value = await client.rpop('list');

• • LLEN: Returns the length of a list.

Copy
1const length = await client.llen('list');

• • LRANGE: Extracts a range of elements from a list.

Copy
1const elements = await client.lrange('list', 0, -1);

• • LMOVE: Atomically moves elements from one list to another.

Copy
1await client.lmove('source', 'destination', 'LEFT', 'RIGHT');

3. Sets

Sets are unordered collections of unique strings. They are useful for tracking unique items, such as unique IP addresses accessing a blog post.

• • SADD: Adds a member to a set.

Copy
1await client.sadd('set', 'member');

• • SREM: Removes a member from a set.

Copy
1await client.srem('set', 'member');

• • SISMEMBER: Checks if a value is a member of a set.

Copy
1const isMember = await client.sismember('set', 'member');

• • SINTER: Returns the intersection of multiple sets.

Copy
1const intersection = await client.sinter('set1', 'set2');

• • SCARD: Returns the number of elements in a set.

Copy
1const count = await client.scard('set');

4. Hashes

Hashes are maps between string fields and string values, making them ideal for representing objects.

• • HSET: Sets the value of a field in a hash.

Copy
1await client.hset('hash', 'field1', 'value1');

• • HGET: Gets the value of a field in a hash.

Copy
1const value = await client.hget('hash', 'field1');

• • HMGET: Gets the values of multiple fields in a hash.

Copy
1const values = await client.hmget('hash', 'field1', 'field2');

• • HINCRBY: Increments the value of a field in a hash by a given number.

Copy
1await client.hincrby('hash', 'field', 1);

5. Sorted Sets

Sorted sets are similar to sets but where every member is associated with a score. They are used to implement leaderboards.

• • ZADD: Adds a member to a sorted set, or updates its score if it already exists.

Copy
1await client.zadd('zset', 1, 'member');

• • ZRANGE: Returns a range of members in a sorted set, by index.

Copy
1const members = await client.zrange('zset', 0, -1);

• • ZRANK: Returns the rank of a member in a sorted set, with the scores ordered from low to high.

Copy
1const rank = await client.zrank('zset', 'member');

• • ZREVRANK: Returns the rank of a member in a sorted set, with the scores ordered from high to low.

Copy
1const rank = await client.zrevrank('zset', 'member');

Expiry

To set the expiry of any key in Node.js using ioredis:

Copy
1import { Redis } from 'ioredis';
2
3const client = new Redis();
4await client.expire('key', time);

Conclusion

Redis is a versatile and powerful tool for any developer’s arsenal. Its various data types and commands allow for efficient data storage and retrieval, making it ideal for high-performance applications. Whether you’re implementing a simple cache, a message broker, or a complex data store, Redis has the tools you need. Happy coding!

#Redis #NodeJS #ioredis #TechLearning