MySQL master-Slave architecture replication principle and configuration detailed

1. Replication overview

MySQL's built-in replication capabilities are the foundation for building large, high-performance applications. The distribution of MySQL data across multiple systems is done by copying data from one of the MySQL hosts to the other host (slaves) and re-executing it again. One server acts as the primary server during replication, while one or more other servers act as slave servers. The primary server writes the update to the binary log file and maintains an index of the file to track the log loop. These logs can record updates that are sent to the slave server. When a primary server is connected from the server, it notifies the primary server where the last successful update was read from the server in the log. Receive any updates from the server from then on, and then block and wait for the primary server to notify the new updates.

Note that when you make a copy, all updates to the tables in the replication must be made on the primary server. Otherwise, you must be careful to avoid conflicts between updates to tables on the primary server and updates made to tables on the server.

1.1 MySQL Supported Replication types:

(1): statement-based replication: SQL statements executed on the primary server execute the same statement from the server. MySQL uses statement-based replication by default and is more efficient.
Row-based replication is automatically selected as soon as it is found that it cannot be copied accurately.
(2): Row-based replication: Copy the changed content past, rather than executing the command from the server again. Support Starting from mysql5.0
(3): Mixed-type replication: statement-based replication is used by default, and row-based replication occurs when a statement-based, inaccurate copy is found.

1.2. Replication-Resolved issues

MySQL replication technology has some of the following features:
(1) Data distribution (distribution)
(2) Load balancing (load Balancing)
(3) Backup (Backups)
(4) High-availability and fault-tolerant lines of availability and failover

1.3 How replication works

As a whole, there are 3 steps to replication:

(1) Master changes the record to binary log (these are called binary log events, binary logs event);
(2) Slave copies the binary log events of master to its trunk logs (relay log);
(3) Slave redo the event in the trunk log and change the data to reflect its own.

Describes the process of replication:

The first part of the process is the master record binary log. Master records these changes in two logs before each transaction update data is complete. MySQL writes the transaction serially to the binary log, even if the statements in the transaction are cross-executed. After the event is written to the binary log, master notifies the storage engine to commit the transaction.
The next step is to slave copy the binary log of master to its own trunk logs. First, slave starts a worker thread--i/o thread. The I/O thread opens a normal connection on master and then starts Binlog dump process. Binlog dump process reads the event from the binary log of master, and if it has been followed by master, it sleeps and waits for master to produce a new event. The I/O thread writes these events to the relay log.
The SQL slave thread (SQL slave thread) handles the last step of the process. The SQL thread reads events from the log and replays the events in them to update the slave data so that it is consistent with the data in master. As long as the thread is consistent with the I/O thread, the trunk log is typically located in the OS cache, so the overhead of the trunk log is minimal.
In addition, there is a worker thread in master: As with other MySQL connections, slave opening a connection in master will also cause master to start a thread. The replication process has a very important limitation-replication is serialized on slave, meaning that parallel update operations on Master cannot operate concurrently on slave.

MySQL master-Slave architecture replication principle and configuration detailed