Starting and ending replication

With CDC Replication, you can mirror data from source tables (using Change Data Capture replication) that are mapped to target tables in Management Console. CDC Replication provides two types of mirroring: Continuous and Scheduled End (Net Change).

As its name implies, Continuous mirroring replicates changes to the target on a continuous basis. Use this type of mirroring when business requirements dictate that you need replication to be running continuously and you do not have a clearly defined reason to end replication at the present time.

These user specified end points ensure that your target database is in a known state when replication ends.

Ending replication allows you to prepare for transitional activities in your business environment and allows you to move to the next step in your business processes. If you are replicating data continuously with Continuous mirroring and business reasons arise that require an end to replication, CDC Replication provides multiple options that suit most business needs. If your business requirements dictate that replication must end at a particular point in your source database log because the target database must be in a known state when replication ends, you can choose from the following options:

• Current time or “Now”
• User-specified date and time
• User-specified log position

If business requirements do not require a specific end point but do require a time frame for ending replication, CDC Replication provides escalating options (Normal, Immediate, and Abort) that end replication more rapidly at the expense of a slower start when resuming replication. For example, a routine end to replication with no particular urgency may require the Normal option, whereas a sudden business need to end replication rapidly may require the Abort option.

You can also refresh all tables or a subset of tables in your subscription depending on your business requirements. A refresh sends a complete copy of data in a source table to the target table and overwrites any existing rows in the target table. Unlike mirroring, a refresh operation with CDC Replication does not require additional database logging which reduces the workload of your source database.

Operational tasks such as starting and ending replication and starting a refresh are normally performed in the Monitoring perspective in Management Console and require Monitor role privileges. Configuration tasks for replication such as flagging tables for refresh, setting or changing the replication method, marking the table capture point, and parking tables are performed in the Configuration perspective of Management Consoled and require Administrator role privileges for read and write access and Operator role privileges for read-only access.