Replication Agent behavior

The following Replication Agent issues are unique to Replication Agent for UDB:

Marking tables immediately after resume when LTM locator is zero

When the Replication Agent instance goes to Replicating state, the Log Reader component reads the primary database transaction log and uses the value of the origin queue ID to determine the position in the log to start reading. When the value of the LTM locator is 0 (zero), the Log Reader starts reading at the end of the log.

Because the Log Reader’s operation is asynchronous, the Replication Agent instance can return to the operating system prompt after the resume command but before the Log Reader has completed its start-up process. If you immediately invoke the pdb_setreptable command to mark a table for replication after the resume command returns, the mark object entry can be placed in the transaction log before the Log Reader finds the end of the log. In that event, the Log Reader will miss the mark table entry and table marking will fail.

To avoid this problem, wait 5 to 10 seconds after invoking the resume command before invoking the pdb_setreptable command to mark a table.

Forcing applications off the database

The DB2 FORCE APPLICATION command causes the data server to drop its connections with an application. The FORCE APPLICATION ALL command causes the data server to drop its connections with all applications.

If you invoke the FORCE APPLICATION command and specify either the Replication Agent application handle or the ALL keyword, the data server drops its connections with the Replication Agent instance. In that event, the Replication Agent receives DB2 error code -30081 and cannot recover, so the Replication Agent instance shuts itself down.

To avoid this situation, invoke the Replication Agent quiesce command before using the DB2 FORCE APPLICATION command.