About PGCluster

PGCluster is the synchronous replication system of the multi-master composition for PostgreSQL .

PGCluster is the replication system of the query base using PostgreSQL.

- 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.

PGCluster consists of three kinds of servers, a load balancer, Cluster DB, and a replication server.


PGCluster has two functions.

- A load sharing function

- 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.

- A high availability function

- 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 isexecuted from the replication server after restoration.


- The Structure of the replication