- Since a replication system is a synchronous replication, delay does not occur with the data duplicate between the Cluster DBs.
- Since a server is multi-master composition, two or more the Cluster DBs can receive access from a user simultaneously.
该架构主要由三种服务器组成:load balancer, Cluster DB, 和 replication server
- The session load of a reference request is distributed. It is effective at the Web application with which a reference request pours in.
- A replication object can be specified per table. When the tables which receive an updating request and a reference request differ, the PGCluster can distribute the table which receives an updating request and can reproduce only the table which receives a reference request.
- When failure occurs in Cluster DB, a load balancer and a replication server separate Failure DB from a system, and continue service using the remaining DB. Since separation of Failure DB and continuation of service are performed simultaneously, most service stop time is made to 0.
- The Cluster DB which repair finished can be dynamically restored to a system, without stopping service.
- Data is automatically copied to DB restored or added from other DB. The query which received during restoration is executed from the replication server after restoration.
从功能介绍看，pgcluster功能很是强大，是基于session请求的，不是介于CPU等资源类型的。复制对象可以是特定表，而且能够把updating和reference请求分开。load balancer 和 replication server能够将发生故障的cluster DB从系统中分开，同时实现了对服务实现了无缝隙的接管，服务不受影响。在无需停止服务的情况下能够动态将修复好的cluster DB加载到系统中。对实现恢复的或者新加入的DB，数据自动进行复制（copy）。