Redis is an open source in-memory database that stores data in the form of key-value pairs. Since the data is stored in memory, Redis is very fast, but every time the Redis service is restarted, the data in it will be lost. Therefore, Redis also provides a persistent storage mechanism to save the data in a file in some form. , data can be automatically loaded from the file into the memory every time it is restarted.
The architecture of Redis consists of two parts: Redis Client and Redis Server. The Redis client is responsible for sending requests to the server and receiving responses from the server. The server side is responsible for processing client requests, for example, storing data, modifying data, etc.
Redis is commonly used as a database, cache and messaging system.
Redis publish and subscribe
Redis provides a publish and subscribe function, which can be used for message transmission. The publish and subscribe mechanism of Redis consists of three parts: publisher , Subscriber and Channel.
The publisher and the subscriber are both Redis clients, and Channel is the Redis server. The publisher sends a message to a certain channel, and subscribers who subscribe to this channel can receive the message. Redis's publish and subscribe mechanism is similar to topic-based publish and subscribe, and Channel is equivalent to a topic.
How many subscriptions can redis support?
Since Redis is based on memory, the number of Redisclient depends on the size of physical memory and there is no fixed number.
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