Master-slave separation implementation technology in MySQL

MySQL is currently the most widely used open source relational database, and its excellent performance, stability and reliability have been widely recognized. As application scenarios become increasingly complex, database scalability becomes increasingly important, and master-slave replication technology is a commonly used technical means to improve MySQL's scalability. This article will introduce the technology of master-slave separation in MySQL.

1. Overview of master-slave replication

Master-slave replication refers to calling one MySQL database the "master database", and any number of other MySQL databases are called "slave databases", and Copy data from the master database to the slave database. Master-slave replication is an asynchronous replication method that is generally used for data replication and data backup in distributed systems. It is very helpful in achieving MySQL high availability and performance expansion.

The master-slave replication architecture is based on binary log and replication thread. The master library records write operations into the binary log, and the slave library copies the binary log of the master library to the local through the I/O thread, and then Replay the operations in this log into your own database through the SQL thread.

2. Master-slave replication scheme

A variety of methods can be used to implement MySQL master-slave replication, such as: file-based replication, row-based replication, hybrid replication, etc.

1. File-based replication

Master-slave replication based on file replication achieves the purpose of replication by synchronizing files on two servers in real time. When the data on the primary server is updated, the binary log file is immediately transferred to the slave server, and the contents of the log file are replayed after the slave server receives it.

The advantages of file-based replication are simple implementation and easy maintenance, but the disadvantages are also very obvious, that is, the placement of the master-slave server limits the replication speed, and it is inefficient when the amount of data is large during the transmission process, and it also needs to be processed Many synchronization issues and errors, security risks, and only suitable for copying small amounts of data.

2. Row-based replication

Master-slave replication based on row replication refers to copying only the changed rows in the data table without copying the entire statement. When the data in the data table changes, MySQL will accurately record the changed rows in the binary log file, and then process it accordingly after receiving this information from the database.

Compared with file-based replication, the advantages of row-based replication are that the amount of data transmitted is smaller, the load of network transmission is reduced, the synchronization efficiency is higher, and the pressure on the main server can be appropriately reduced. However, its disadvantage is that it is difficult to implement, requiring multiple network transmissions and detailed data analysis. Improper operation may cause delays and errors in data synchronization.

3. Hybrid-based replication

Hybrid-based replication is a replication method that mixes file replication and row replication technologies. In MySQL, you can choose the replication method by modifying parameters.

The advantage of hybrid-based replication is that it can take into account the ease of maintenance of file-based replication and the high efficiency of row-based replication. Its disadvantage is that compared with the single replication method, it is more complex and more difficult to implement.

3. Master-slave replication architecture

Before setting up master-slave replication, it is necessary to determine the replication architecture, including the deployment of the master and slave libraries.

1. Deployment of the main library

The main library is the source of data writing and updating, so the deployment of the main library requires attention to high availability and data security. Under normal circumstances, it is recommended to deploy the main database in a cluster mode, which can ensure high availability and fault tolerance of data. If the main database node is deployed on the same server, the server may be down at any time, which will have a serious impact on the availability of the main database.

2. Deployment of slave libraries

The slave library is used to implement data backup and reading. The number of slave libraries is relatively large and can be increased or decreased as needed. The deployment of the slave library requires attention to data security and read performance. The slave library needs to quickly copy the data of the master library without affecting the data writing of the master library.

You need to follow the following principles when deploying the slave library:

(1) Avoid running on the same server as the main library to avoid excessive load and difficulty in ensuring data security and availability.

(2) The better the hardware configuration of the slave library, the higher the performance and the faster the data synchronization speed.

(3) Under the asynchronous replication mechanism, there is a certain delay in data update from the slave database, so it is not suitable for scenarios with particularly high transaction requirements.

(4) The connection between the slave library and the main library is based on IP address or domain name, so it is necessary to avoid the main library and the slave library being in different subnets to avoid network delays affecting the data synchronization speed.

4. Implementation of master-slave replication

We can implement master-slave replication through the change master command, which needs to be executed on the slave database. The change master command content mainly includes the following parts:

1. master_host: the IP address or domain name of the main library.
2. master_port: The port number of the master library.
3. master_user and master_password: username and password of the main library.
4. master_log_file and master_log_pos: The location information read by the slave library from the main library binary file.

After completing the change master command, execute the start slave command to achieve master-slave synchronization.

5. Optimization of master-slave replication

1. Increase restricted tables: You can enable binlog_do_db through configuration parameters to limit the tables that need to be synchronized to reduce the size of the binary log and improve the data synchronization speed.
2. Modify logging frequency: You can reduce the transactions involved by adjusting the frequency of MySQL logging. If you adjust the synchronization gap to a larger value, you can reduce transaction and synchronization delays caused by various reasons.
3. Add I/O threads: You can increase the data synchronization speed by adding I/O threads.
4. Upgrade hardware configuration: Increasing the server's CPU, memory, hard disk and other configurations can improve the performance and speed of the entire replication system.

6. Summary

MySQL master-slave replication technology is an important technical means to achieve high availability and performance expansion. Through reasonable selection of replication methods, combined with appropriate distributed system architecture and Optimizing the above parameters can achieve an efficient and stable master-slave replication system, which is also of great significance for improving the scalability of MySQL.

The above is the detailed content of Master-slave separation implementation technology in MySQL. For more information, please follow other related articles on the PHP Chinese website!