What scenarios is redis suitable for?

What scenarios is redis suitable for?

1. Caching

Caching is now a must-have for almost all medium and large websites. Reasonable use of caching can not only improve website access speed , and can also greatly reduce the pressure on the database. Redis provides key expiration function and flexible key elimination strategy. Therefore, Redis is now used in many caching situations. (Recommended: "Redis Video Tutorial")

2. Ranking

Many websites have ranking applications, such as JD.com’s monthly Sales list, product new arrival ranking by time, etc. The ordered set data structure provided by Redis can implement various complex ranking applications.

3. Counter

What is a counter, such as the number of views of products on e-commerce websites, the number of video plays on video websites, etc. In order to ensure the real-time performance of the data, 1 must be given for each browsing. When the concurrency is high, it will undoubtedly be a challenge and pressure to request database operations every time. The incr command provided by Redis implements counter functions and memory operations with very good performance and is very suitable for these counting scenarios.

4. Distributed session

In cluster mode, when there are not many applications, it is generally sufficient to use the session replication function that comes with the container. When the number of applications increases, In relatively complex systems, session services centered on in-memory databases such as Redis are generally built. Sessions are no longer managed by containers, but by session services and in-memory databases.

5. Distributed lock

Distributed technology is used in many Internet companies. The technical challenge brought by distributed technology is the concurrency of the same resource. Access, such as global ID, inventory reduction, flash sales and other scenarios. Scenarios with low concurrency can use pessimistic locks and optimistic locks of the database. However, in scenarios with high concurrency, it is necessary to use database locks to control concurrent access to resources. It is not ideal and greatly affects the performance of the database. You can use the setnx function of Redis to write distributed locks. If the setting returns 1, it means the lock acquisition is successful. Otherwise, the lock acquisition fails. There are more details to consider in actual applications.

6. Social Network

Likes, dislikes, following/being followed, mutual friends, etc. are the basic functions of social networking sites. Generally speaking, the number of visits to social networking sites It is relatively large, and the traditional relational database type is not suitable for storing this type of data. The hash, set and other data structures provided by Redis can easily realize these functions.

7. Latest list

Redis list structure, LPUSH can insert a content ID as a keyword at the head of the list, LTRIM can be used to limit the number of lists, so that the list There are always N IDs. There is no need to query the latest list, just go to the corresponding content page based on the ID.

8. Message system

Message queue is a must-have middleware for large websites, such as ActiveMQ, RabbitMQ, Kafka and other popular message queue middleware, which is mainly used for business solution Coupling, traffic peak shaving and asynchronous processing of services with low real-time performance. Redis provides publish/subscribe and blocking queue functions, which can implement a simple message queue system. In addition, this cannot be compared with professional message middleware.

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