Key-value distributed storage system has the advantages of fast query speed, large amount of stored data and high concurrency, which is very suitable for primary key query, but it can not carry out complex conditional query.

If the real-time search engine is used for complex conditional retrieval and full-text retrieval, it can replace relational databases with low concurrency such as MySQL, achieve high concurrency and high performance, and save dozens of times the number of servers.

Key-value distributed storage represented by MemcacheDB and Tokyo tyrant can easily complete high-speed queries under tens of thousands of concurrent connections. MySQL basically crashed under hundreds of concurrent connections.

On this basis, redis supports sorting in various ways. Like memcached, data is cached in memory to ensure efficiency. The difference is that redis will periodically write updated data to disk or modify additional record files, and on this basis, master-slave synchronization will be realized.

Extended data:

Jedis main memory protection is an important part of storage protection. Main memory protection generally includes storage area protection and access mode protection. The storage area can be protected by boundary registers, and the contents of the upper and lower registers are given by the system software through privileged instructions, so as to delimit the area of each user program and prohibit cross-border access.

Jedis only allows access operations when two keys match to protect other program areas from infringement. Ring protection is to layer system programs and user programs according to their importance, which is called rings, and each ring provides access levels to it. The access operation in violation of regulations is illegal to protect the program being executed.

Baidu Encyclopedia-Key-Value