Learn about Memcached caching technology

Memcached is a common caching technology that can be used to cache common data such as database query results, API responses, and Web pages. Usually, Memcached runs on multiple servers, which form a distributed high-availability cache cluster to provide higher availability and scalability.

Memcached main features and advantages:

1. Fast: Memcached can process and retrieve data very quickly and effectively reduce the pressure on the back-end server.
2. Scalability: Memcached can increase its capacity and performance by adding new cache nodes, making it ideal for large web applications.
3. Multi-threading support: Memcached can be written in a variety of programming languages, supports multi-threaded operations, and is compatible with modern web technologies such as Node.js and Golang.
4. Automatic distribution: Memcached will automatically distribute data to different servers, and automatically switch to other servers when a server goes down.

However, Memcached also has some limitations and weaknesses:

1. Size limit: By default, there is a limit to the size of data that Memcached can store, and the default is 1MB. Although it is possible to modify the configuration file, this will also increase memory pressure.
2. Data life cycle: If the data expires or becomes obsolete, Memcached will automatically delete the data. This means that data must be checked regularly and updated, otherwise data inconsistencies may result.
3. Disk support: Memcached only supports memory cache and cannot be stored on disk. If the server restarts or is powered off, the cache will be lost.

Note:

1. Memcached is not the main data store: Memcached is only used for caching, and the main source of data is still the main data store such as the database.
2. Multiple caching layers can be used: In addition to Memcached, other caching layers such as Redis and Varnish can be used in conjunction with it to improve performance and availability.
3. For High-QPS: Memcached is more suitable for high-concurrency and high-QPS scenarios, rather than applications that need to support complex queries and data transformations. When it is necessary to support complex queries and calculations, relational databases such as MySQL and PostgreSQL are more suitable.

Conclusion:

Memcached is an excellent caching tool that has been widely used in web applications. It has many great features, but also has some limitations and drawbacks. In actual use, in-depth thinking and trade-offs are required based on the scenario.

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