solidDB® advanced replication data synchronization ensures that once data is committed in one database of a advanced replication configuration, data is never lost during synchronization between databases. The advanced replication Store and Forward Messaging feature ensures that before sending a synchronization message from one database to another, the message is stored on the originating database. Similarly, the message is stored in the receiving database before it is executed in the receiving database. Once the stored messages become obsolete, they are deleted.
Because Store and Forward Messaging stores data persistently to disk, it causes some overhead in the synchronization process. When a message holds less data for synchronization, the overhead is significantly higher. For example, when you send a synchronization message that contains one transaction between databases, it may take up to one second to complete the messaging roundtrip, whereas when you synchronize a few dozen transactions within one message, it still typically takes less than one second.
To minimize the overhead caused from Store and Forward Messaging, be sure to create synchronization messages that contain more than one transaction. While you are not prohibited from synchronizing a single transaction in a message, doing so has significant adverse performance implications, especially if your site has high transaction volume. Before you use single transactions (or few transactions) in a single synchronization message, consider if there are any critical performance and scalability requirements for the databases at your site.
Using RPC message compression with synchronization
solidDB® supports message compression for all network traffic between client and server. In data synchronization, the replica database server acts as a client and master database server acts as a server. Therefore, the message compression utility that is available for Client/Server communication, is also available for advanced replication's Server-to-Server communication.
You can set the message compression on by specifying "-z" parameter in the connect string given in the SET SYNC CONNECT command in replica database server. For example:
SET SYNC CONNECT ’tcp -z masterserver 1315’ TO MASTER myMaster
The data compression's effect on performance depends heavily on the compressibility of the data and on the available bandwidth. In very fast networks the increased CPU consumption caused by compression & decompression of the messages may outweigh the performance gain achieved by smaller network messages. Generally, the slower the network is, the more positive impact network traffic compression may have in the overall performance.