Asymmetric Replications

Proxima Ceny

Current Situation

The current existing system in operation is at the end of its life cycle. We have decided to develop a new, more productive and highly stable system. The data structure of the original system is absolutely insufficient, completely new structures are required. The data is divided into a number of tables in the original system, while the new one contains just one table for every area. Simply said, the new system will be completely re-organised.

Extremely valuable data is contained in the original system though. The volume has long ago exceeded one quarter of a billion entries and it is only a question of time when the original system is going to stop working. The original client is also written in an environment whose support disappeared along with Windows XP and is non-transferrable to Windows7/8.

One solution for building the new system is using migration scripts, migrate the data, shut down the original system and start the new one. This solution is of course possible, however highly risky.


Asymmetric replications enable the transition to a new database system without the risk and stressAsymmetric replication enables a stress-free and risk-free transfer to a new system database. The implementation of the new system is done without business interruption. Before you turn off the original system, both systems can operate simultaneously.

The customer has time to gradually train the staff and administration; implementation is therefore no load on staff. These requirements satisfy asymmetric replication and migration, which is a communication between structurally very different sources.

Standard status in many companies where the original system loses its ability to meet the increasing demands of management. Original system yet has strategic data, without which company cannot do even for a moment. The standard implementation of the new system carries the risk of trial operation. The asymmetric replication can be test run so long as the customer wants. This is not a radical cut. Both systems operate in parallel as long as needed. At the same time do not produce dramatically increased demands on the staff. Whenever is possible to specify the initial intentions. The original system can be turned off while the new one will definitely work.

Asymmetric replication ensures that data is not maintained laboriously at two locations. The changes in the original system are reflected in the new system, as well as from new to the original. This system includes a number of ways data transformations that are defined in the replication bridge. Since replication between two tables with different structures to quite different data storages.

System of a new database has built-in mechanisms that prevent the unrestrained development. Clear development rules forces developers follow the defined rules and significantly reduce errors in developed data structures. Never can be made changes in the production database directly, but any changes are made ​​to the development database and debugging of the changes are pushed to production database by differentiation procedures.

The original philosophy is based on the Microsoft SQL Server replication. It is also used MSDTC for remote transactions between servers. Philosophically exists Publisher, Subscriber and Distributor, LogReader and Distribution Agent. With the replication philosophy the similarity ends. Standard replication processes are replaced by a special procedure library, triggers and system tables, allowing asymmetric traffic between differently structured data.

This system is applied to real data with half a billion records.