2.使用向外扩展的方法来提高数据库系统的总体处理能力: You can use replication as a scale-out solution, i.e. where you want to split up the load of database queries across multiple database servers, within some reasonable limitations.
Because replication works from the distribution of one master to one or more slaves, using replication for scaleout works best in an environment where you have a high number of reads and low number of writes/updates. Most websites fit into this category, where users are browsing the website, reading articles, posts, or viewing products. Updates only occur during session management, or when making a purchase or adding a comment/message to a forum.
Replication in this situation enables you to distribute the reads over the replication slaves, while still allowing your web servers to communicate with the replication master when a write is required.
