Day 2 Mysql Replication

Day 2 Mysql Replication

I am a programmer , I have my computer so i can do everything , I am good.————Michael Wideneus （MySQL之父）

Replication is based on the master server keeping track of all changes to its databases (updates, deletes, and so on) in its binary log.
复制是通过将所有数据库修改操作记录（更新，删除等）到了日志文件中的主服务器实现的。

The binary log serves as a written record of all events that modify database structure or content (data) from the moment the server was started.
日志服务器担负着将各类修改记录写入日志文件的职责。从日志服务器被启动的那一刻起，所有修改了数据库结构或者数据的事件，都会被它记录下来。

Typically, SELECT statements are not recorded because they modify neither database structure nor content.
一般来说，SELECT语句不会被记录下来，因为他们既不会影响数据库的结构，也不会影响数据库的数据。

Each slave that connects to the master requests a copy of the binary log.
每台接上了主服务器的从服务器都会请求一份二进制日志的拷贝文件。

That is, it pulls the data from the master, rather than the master pushing the data to the slave.
那就是，“从服务器”从“主服务器”那里将日志拉取回来，而非主服务器向从服务器推送日志。

The slave also executes the events from the binary log that it receives. This has the effect of repeating the original changes just as they were made on the master.
从服务器会将它收到的二进制日志中所记录的事件再执行一遍，这样就起到了重复这些操作的效果，就好像这些操作在主服务器上被执行时一样。

Tables are created or their structure modified, and data is inserted, deleted, and updated according to the changes that were originally made on the master.
根据主服务器对于各类操作的记录，从服务器上的数据表会相应地被创建或修改、而从服务器上的数据也会被相应地插入、删除或更新。

本文选自：
https://dev.mysql.com/doc/mysql-replication-excerpt/5.5/en/replication-implementation.html