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2.6.6 Replication

IBM solidDB is equipped with three data replication technologies:

Advanced replication

This method to disseminates parts of a master database to remote locations called replicas. With extended SQL syntax, a master user can define publications (with CREATE PUBLICATION) being views of a database. Users at replicas can subscribe to those publications and request data refreshes. Propagation of updates from the replicas to the masters is also possible. Because permanent connections between the masters and replicas are not required, advanced replication is suitable for applications operating in loosely connected networks, for example with mobile replica devices.

HotStandby replication

The solidDB HA product called solidDB HotStandby applies continues transactional replication between the active node and the standby node. A user can make no choices about the replicated data: the whole database is always replicated. However, controls (both configuration parameters and ADMIN COMMANDs) exist so that the user can start and stop the replication, and change the characteristics. Both synchronous and asynchronous replication modes are possible. The solidDB HA solution is described in Chapter 5, “IBM solidDB high availability” on page 109.

Logreader API

If none of the these replication methods fit the user’s needs, one can develop a custom replication solution using the logreader. Logreader is a component in the server, externalizing the contents of the transaction log. With the log reader, all changes made to the database can be read from the log and transferred elsewhere. The interface is in the form of a SELECT statement reading from a virtual (non-existing physically) table called SYS_LOG. The log reading is done through a standard ODBC/JDBC interface and thus it can be executed both locally and remotely. The replication solution used in solidDB Universal Cache is based on the logreader.

Chapter 2. IBM solidDB details 35

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