Commercial multi-master replication for PostgreSQL
According to an announcement by EnterpriseDB, the commercial xDB-Replication software for the open source PostgreSQL database now offers the option to use multi-master replication. The feature is still in beta and is only available for 64-bit Linux; it is designed to work with PostgreSQL from version 8.4. EnterpriseDB plans to support other operating systems such as Solaris, Windows, HP-UX and 32-bit Linux in the future.
Multi-master replication allows multiple computers to write into the same database tables, which accelerates data write operations. With the more basic master-slave replication, only one computer ("master") accepts new or modified data and then passes it on to all the others ("slaves"). All slaves can read.
Multi-master replication also requires one main computer to be the reference for all other masters. From this computer, the other masters can initially, or after a crash, obtain all data including schema definitions. During operation, every computer will pass its modified data on to this master server, which will forward it to the other masters.