PHP operation Redis example explanation

1. Concept

redis is a key-value storage system. Similar to Memcached, it supports relatively more stored value types, including string (string), list (linked list), set (set), zset (ordered set) and hash (hash type). These data types all support push/pop, add/remove, intersection, union, difference, and richer operations, and these operations are all atomic.

Redis supports various sorting methods. Like memcached, data is cached in memory to ensure efficiency. The difference is that redis will periodically write updated data to disk or write modification operations to additional record files, and on this basis, master-slave (master-slave) synchronization is achieved.

2. Installation and use of Reids

1. Installation: Linux system can download the source code package for compilation through the official website address: http://redis.io/download Installation
2. Start the Redis service command:
(1)redis-server
(2)service redisd start
3. Commonly used commands for Redis:
(1)Connect: redis- cli -h -p -a
(2) Test whether it is available: enter PING and return PONG response
(3) You can set the key and value values ​​through "SET key value";
(4) Get the Value value corresponding to the Key through "GET KEY".

3. Commonly used methods of operating Redis in PHP

1. PHP comes with the Redis class, which is used as an extension to operate Redis, so it can be performed through this class Connection:
$redis = new Redis();
$redis->connect('',);
$redis->auth('< Optional, password>');

2. Normally, because Redis supports five data types: string, hash, list, set and zset, Redis is often used as both a cache and a queue in development. Kinds of services:
(1) PHP example of Redis used as cache:

 $redis->set(<key>,<value>); //设置key和value的键值对
 $redis->get(<key>);//获取Key对应的Value值
 (2)Redis用作锁的操作：
 $redis->setnx(<key>,<value>); //设置key和value的键值对，如果key的value已经存在则不操作
 $redis->get(<key>);//获取Key对应的Value值
 (3)Redis用作队列的PHP示例：
 $redis->lpush(<key>,<value>);//从列表头部插入数据，列表名为key
 $redis->lpop(<key>);//从列表尾部去除并移除数据，列表名为key

4. Summary of PHP operation Redis methods

In addition to the above common operations, PHP also Supports various data type operations used by Redis, such as mset, hset, etc.

5. Characteristics and performance of Reds

1. Redis is a very fast non-relational database that can store keys and 5 different types of values. Mapping between key-value pairs stored in memory can be persisted to the hard disk. Replication features can be used to expand read performance, and client sharding can also be used to expand write performance;
2. When data Dependencies are no longer needed. The memory-based nature of Redis is very efficient compared to a database system that writes every change to the hard disk when executing a transaction. There is no obvious difference in the speed of writing and reading operations;

3. Comparison with other data storage methods:

4. Advantages of using Redis:
(1) There is memcached Readers with experience may know that users can only use the APPEND command to add data to the end of an existing string. The memcached documentation states that you can use the APPEND command to manage the element list. This is good! Users can append elements to the end of a string and use that string as a list. But how do you then remove these elements? The method used by memcached is to use a blacklist to hide the elements in the list, thereby avoiding operations such as reading, updating, and writing (or database requests and memcached writes) on the elements. In contrast, Redis's LIST and SET allow users to add or delete elements directly.

(2) Using Redis instead of memcached can solve this and other problems. It not only makes the code shorter, easier to understand, and easier to maintain, but also makes the code run faster ( Because the user does not need to read the database to update the data). In addition to this, Redis's efficiency and ease of use are much better than relational databases in many other situations.

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