Data persistence methods in PHP

In recent years, with the development and popularization of the Internet and the increase in Web applications, data persistence has become particularly important. In traditional web applications, data is usually stored and managed using relational databases, such as MySQL, PostgreSQL, etc. However, as web application development becomes increasingly complex and diversified, problems caused by database management are becoming more and more prominent, such as:

1. Database read and write speed limit formula
2. Concurrency processing capability of database
3. Cost and difficulty of database maintenance

Therefore, some new technologies have emerged, the most popular of which is to store data in memory Caching technologies, such as Memcached and Redis, etc. In addition, there is a technology called data persistence, which seems to be able to overcome many problems caused by database management and improve the reliability and performance of web applications to a certain extent.

Data persistence is an in-memory database technology that stores data in memory, but the data can be restored after the server is shut down or fails. The main advantages of data persistence technology are as follows:

1. Reduce disk IO
2. Storage and management independent of external database
3. Greatly improves response Speed, especially when reading a large amount of data

Data persistence technology is generally based on binary trees or B-trees, which is called "data structure persistence". In data structure persistence, we can modify the data structure while retaining the previous state. The advantages of this technology are data history and rollback, etc., as well as data comparison between multiple versions. Of course, this technique requires additional storage space due to the historical nature of the data. Therefore, compared with basic data structures, the persistence of data structures requires richer storage space and higher storage technology.

In PHP, there is a widely used data persistence method called "PHP Poisson memory hash table". Its implementation is based on the "Poisson distribution" algorithm, which can store and retrieve data efficiently without reading or writing from the hard disk.

PHP Poisson in-memory hash table was developed in 2002 by Dr. Andi Gutmans and his colleague Zeev Suraski. It implements a fast hash table by porting the object engine from JavaScript to PHP. PHP Poisson in-memory hash table provides a very powerful caching technology, which allows to store data in memory and easily retrieve and update them without accessing the hard disk or database.

When using the PHP Poisson memory hash table, we need to set some parameters, such as the size of the hash table, load factor, expansion factor, etc. These parameters mainly affect the performance and memory utilization of hash tables. In PHP, we can use extensions such as memcache and APC to implement PHP Poisson memory hash tables and other aspects of caching technology.

In short, data persistence is a very useful technology that can significantly improve the performance and reliability of web applications. In PHP, the PHP Poisson in-memory hash table is a very popular and efficient implementation that can easily store data in memory and perform fast retrieval and update operations. If you are developing a web application and want to improve its performance and reliability, PHP Poisson in-memory hash tables are a technology well worth trying.

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