Transaction Handling with Replication Server

Replication Server depends on data servers to provide the transaction-processing services needed to protect stored data.

To ensure the integrity of distributed data, data servers must comply with the following transaction-processing conventions:

A transaction is one unit of work. Either all operations in the transaction are performed or none are performed.
Transaction results are permanent. A transaction cannot be arbitrarily undone after it is committed.

Replication Server copies committed transactions from primary sites to replicate sites, and distributes transactions in the order they are committed so that copied data passes through the same states as the primary data.

This figure illustrates the Replication Server method for translating transactions.

The figure illustrates Replication Servers method for translating transactions. Replication Server copies committed transactions from the primary data server using L T L to destination sites. It distributes transactions in the order they are committed so that copied data passes through the same states as the primary (source) data. Once the primary Replication Server sends transactions to subscribing sites, destination Replication Server store the transactions in the outbound Data Server Interface (D S I) stable queue. From the stable queue the data is sent to the destination Data server using transact dash Sequel.

Once the primary Replication Server sends transactions to subscribing sites, destination Replication Servers store the transactions in the outbound Data Server Interface (DSI) stable queue.

Stable Queues
When you install Replication Server, you set up a disk partition that Replication Server uses to establish stable queues. During replication operations, Replication Server temporarily stores updates in these queues.
Distributed Concurrency Control
Data servers that store primary data provide most of the concurrency control needed for the distributed database system. If a transaction fails to update a primary version of a table, the primary Replication Server does not distribute the update to other sites.
Transaction Processing by the Replication Agent
The Replication Agent scans the database transaction log and sends transaction information to Replication Server for distribution to subscribing databases. Learn the transaction processing by Adaptive Server RepAgent thread.

Parent topic: Replication Server Technical Overview