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Editor to share with you what the benefits of using redis, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to know it!

What are the benefits of using redis?

(1) it is fast, because the data is stored in memory, and the advantage similar to HashMap,HashMap is that the time complexity of search and operation is O (1).

(2) supports rich data types and string,list,set,sortedset,hash

1) String

Common commands: set/get/decr/incr/mget, etc.

Application scenario: String is the most commonly used data type, and ordinary key/value storage can be classified as this type.

Implementation: String is stored in redis as a string by default, which is referenced by redisObject. When it encounters incr, decr and other operations, it will be converted to numeric calculation. In this case, the encoding field of redisObject is int.

2) Hash

Common commands: hget/hset/hgetall, etc.

Application scenario: we need to store a user information object data, including user ID, user name, age and birthday. Through the user ID, we want to get the user's name or age or birthday.

Implementation: the Hash of Redis is actually an internally stored Value as a HashMap, and provides direct access to this Map member. As shown in the figure, Key is the user ID,value is a Map. The key of this Map is the property name of the member, and value is the property value. In this way, the modification and access of the data can be directly through the Key of the internal Map (the key of the internal Map is called field in Redis), that is, the corresponding attribute data can be manipulated through key (user ID) + field (attribute tag). Currently, there are two ways to implement HashMap: when the number of HashMap members is relatively small, Redis will use a compact storage method similar to an one-dimensional array in order to save memory, instead of using the real HashMap structure, then the encoding of the corresponding value redisObject is zipmap, and when the number of members increases, it will be automatically converted to the real HashMap, and the encoding will be ht.

3) List

Common commands: lpush/rpush/lpop/rpop/lrange, etc.

Application scenarios: there are many application scenarios of Redislist, and it is also one of the most important data structures of Redis. For example, twitter's watch list, fan list and so on can be implemented using Redis's list structure.

Implementation: the implementation of Redislist is a two-way linked list, that is, it can support reverse search and traversal, which is more convenient to operate, but it brings some additional memory overhead. Many implementations within Redis, including sending buffer queues, also use this data structure.

4) Set

Common commands: sadd/spop/smembers/sunion, etc.

Application scenario: the external function provided by Redisset is similar to that of list, except that set can arrange weights automatically. When you need to store a list of data and do not want to have duplicate data, set is a good choice, and set provides an important interface to determine whether a member is in a set collection, which list cannot provide.

Implementation: the internal implementation of set is a HashMap whose value is always null. In fact, it quickly arranges the weight by calculating hash, which is why set can determine whether a member is in the collection or not.

The above is all the contents of this article entitled "what are the benefits of using redis?" Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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