Where is the distributed cache mainly used?

Distributed cache is mainly used to reduce the pressure on the database and improve the response speed and concurrent throughput of the system in a high concurrency environment. When a large number of read and write requests flock to the database, the processing speed of disk and memory is obviously not an order of magnitude. Therefore, adding a layer of cache in front of the database can significantly improve the response speed of the system and reduce the pressure on the database. As a traditional relational database, MySQL provides complete ACID operations, supports rich data types, powerful associated queries, where statements and so on. , you can easily establish query indexes and perform complex operations such as internal connection, external connection, summation, sorting and grouping. , and supports functions such as stored procedures and functions. This product has high maturity and powerful functions. However, for scenes that need to handle high concurrent access and store massive data, many powerful functions of traditional relational databases have to be abandoned for performance, which sacrifices the usability of the system and makes the design and management of the system more complicated. This also makes another new storage solution-NOSQL popular in the past few years. The biggest difference between it and the traditional relational database is that it does not use SQL as the query language to find data, but uses key-value form to find data, which provides higher query efficiency and throughput, and can more conveniently expand and store massive data, partition on thousands of nodes, and automatically copy and back up data. In the distributed system, message, as a communication method between applications, has been widely used. Messages can be stored in the queue until they are retrieved by the receiver. Because the message sender does not need to wait for the response of the message receiver synchronously, the asynchronous reception of messages reduces the coupling degree of system integration, improves the efficiency of distributed system cooperation, and enables the system to respond to users faster and provide higher throughput.

When the system is under peak pressure, the distributed message queue can also be used as a buffer, which can reduce the pressure of the cluster and avoid the whole system being crushed. Vertical search engine plays a very important role in distributed system. It can not only meet the needs of users for full-text retrieval and fuzzy matching, but also solve the problem of low efficiency of similar queries in the database. It can also solve the problem that multi-table association or complex query cannot be carried out in distributed environment because different databases and tables are used or NoSQL database is used.