Detailed explanation of the application of Redis in Node.js

Redis is an efficient memory-based cache and database. It is fast, reliable and easy to use. It is widely used in web applications and supports a variety of data types, such as strings, hash tables, lists, sets, ordered sets, etc. Node.js, as an event-driven asynchronous JavaScript runtime environment, is gradually increasing in popularity in web development. Redis provides Node.js API driver and some convenient Node.js libraries, which makes Redis very widely used in Node.js development.

Why choose Redis?

Before introducing the application of Redis in Node.js, let’s first take a look at why we chose Redis. The emergence of Redis is to solve the problem of performance bottlenecks caused by the gradual increase in access to relational databases. The characteristic of Redis is that it uses the main thread to complete read and write operations, ensuring efficient operation. Redis stores data in memory, which allows it to have very high read and write speeds, reducing the time of I/O operations and disk access. In high concurrency situations, Redis can better handle requests and improve system stability and response speed.

Using Node.js and Redis allows us to easily perform caching and data storage operations in Node.js without connecting to a complex database. In addition, the use of Redis can also improve performance and scalability, and is easy to deploy and operate.

Redis driver

Redis provides multiple Redis drivers for use with the Node.js API. The most commonly used ones are node-redis and ioredis. node-redis is currently the most popular and stable driver, while ioredis provides higher-level functions such as sentinels and cluster management, and also supports more Redis commands. No matter which Redis driver is used, they all provide a connection between Node.js and Redis, which can easily realize data reading and writing operations.

Installing and Configuring Redis

To use Redis and Node.js, you need to install Redis first, and then configure the Redis driver in Node.js. In Windows systems, you can go to http://redis.io/download to download the installation package, and in Unix systems, you can install it through the following command:

$ wget http://redis.googlecode.com/files/redis-2.4.16.tar.gz
$ tar xvzf redis-2.4.16.tar.gz
$ cd redis-2.4.16
$ make

After Redis is installed successfully, you can install Node.js Redis driven. Installing the Redis driver in Node.js is easy, just use the npm install command on the command line. For example, to install node-redis, you can use the following command:

$ npm install redis

Redis Basic Operation

The first step is to establish a connection with the Redis server. The node-redis module in Node.js can establish a connection using the following code:

var redis = require('redis');
var client = redis.createClient();

This allows us to perform basic operations on the Redis server, written in JavaScript language in Node.js. Let's take a look at how to use Node.js and Redis for basic operations.

Set value

The following will set a key-value pair in Redis to demonstrate how to use Node.js and Redis to perform basic operations.

client.set('key', 'value', function(err, response) {
  console.log(response);
});

In the set operation here, the first parameter key is the key name that needs to be set, and the second parameter value is the value that needs to be set. Next, we can use the callback function to receive the return value from the Redis server. For simple operations, the return value is usually OK.

Get the value

Getting a key-value pair in Redis is very easy. The following code can obtain the key-value pair set in the previous step and print the result to the console.

client.get('key', function(err, response) {
  console.log(response);
});

The first parameter key in the get operation here is the key name to be obtained, and the second parameter is the callback function used to receive the value returned by the Redis server.

Set expiration time

The key-value pair of Redis can set the expiration time, which means that a certain key-value pair will expire within the specified time. The code below sets up a key-value pair and sets the expiration time to five minutes.

client.set('key', 'value', 'EX', 300, function(err, response) {
  console.log(response);
});

The 'EX' here is the built-in command of Redis. The number after . represents the expiration time to be set, in seconds. After performing the above operations, this key-value pair will automatically expire after five minutes.

Delete key-value pairs

Although Redis provides a way to set the expiration time, in some cases, we may need to manually delete a key-value pair. The code below shows how to delete a key-value pair using Node.js and Redis.

client.del('key', function(err, response) {
  console.log(response);
});

The first parameter key in the del operation here is the key name that needs to be deleted, and the second parameter is the callback function used to receive the value returned by the Redis server.

The above are the most basic settings, acquisition and deletion operations of Redis. The combination of Node.js and Redis makes these operations very simple. In addition, Redis also supports more operation types, including lists, hash tables, sets, etc. We can perform these operations in Node.js through the Redis driver.

Node Redis Cluster

In order to improve the availability of Redis, a cluster mode is adopted in terms of sharding and replication, which allows multiple Redis nodes to be integrated together to form a Redis cluster. . The usage of Redis cluster in Node.js is almost the same as single Redis node. We can use the API provided by node-redis to operate the Redis cluster.

Using Redis cluster in Node.js must use ioredis driver. The sample code is as follows:

const Redis = require('ioredis');

const nodes = [
  { port: 6379, host: '172.16.0.1' },
  { port: 6379, host: '172.16.0.2' },
  { port: 6379, host: '172.16.0.3' },
  { port: 6379, host: '172.16.0.4' },
  { port: 6379, host: '172.16.0.5' },
  { port: 6379, host: '172.16.0.6' },
];

const redis = new Redis.Cluster(nodes);

The above is a code example when using Redis cluster in Node.js. To use Redis cluster, just specify multiple Redis managed instances.

summary

Through the introduction of this article, we can find that the use of Redis in Node.js is very convenient and convenient. Node.js provides many excellent Redis drivers to simplify our interaction with Redis. Redis's efficiency and scalability make it a widely used caching and database solution in Node.js. You only need to follow the steps introduced in this article to easily integrate Redis into your Node.js application and improve the performance and response speed of your web application.

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