Administration Guide

Replicating Data

Replication is the process of taking changes stored in the database log at the source server and applying them to the target server. You can use replication to define, synchronize, automate, and manage copy operations for data across your enterprise. You can automatically deliver the data from a host system to target sites. For example, you can copy data and applications to branch offices, retail outlets, and even sales representatives' laptops.

The two operational components in replication are Capture and Apply. The Capture component captures changes made to data in source tables which have been defined for replication by reading the database log. The Apply component reads the changed data previously captured and stored in a change data table and applies it to the target tables.

Using the Control Center, you can do the setup required for replication using the Define as replication source and Define subscription actions. The replication components Capture and Apply run outside the DB2 administration tools.

Replication administrators can perform the following actions from the Control Center:

• Define replication sources
• Define replication subscriptions
• Specify SQL to enhance data during the apply process

The high-level steps for replicating data are as follows. Refer to the Replication Guide and Reference for details.

1. Design a replication scenario (map the source and target tables).
2. Define a replication source (this relates to the capture action).

To define a replication source:

1. Specify source columns to capture.
2. Choose replication options.
3. Define a replication subscription (this relates to the Apply action).
4. Alter the source table with the Data Capture Changes option.
5. Start Capture to read and store data changes.
6. Start Apply to replicate changes to target tables.

To define a replication subscription:

1. Name the subscription set.
2. Specify the database and target table.
3. Specify the target columns.
4. Specify the row selection.
5. Specify SQL for run-time processing.
6. Set the subscription timing.