The performance and operation of IBM DB2 Universal Database primary data servers in a Sybase replication system might be affected as follows:
The IBM DB2 Universal Database transaction log is affected in the following ways:
Replication requires a before and after image of each row that is changed. When you mark a primary table for replication, the table is altered with the DATA CAPTURE CHANGES clause. As the number of tables marked for replication increases, so does the DASD space requirement for the IBM DB2 Universal Database active log data sets.
Using Replication Agent for DB2 UDB increases the amount of data stored in IBM DB2 Universal Database logs. The size of the increase depends on the number, type, and size of the primary tables, and the types of transactions replicated. For example, update transactions require both before and after images, and they include all of the columns in a row, even if those columns do not change. For more detailed information, see the Replication Agent for DB2 UDB documentation.
Two Replication Agent system tables are created in the primary IBM DB2 Universal Database when the Replication Agent is installed:
LTMOBJECTS contains a row for each primary table marked for replication. Its size depends on the number of tables marked for replication.
LTMLASTCOMMIT stores information about the most recent replicated transaction successfully committed in the replicate database. The size changes according to the number of primaries that are replicated into the IBM DB2 Universal Database, when it is a replicate database.
Unless the primary IBM DB2 Universal Database also serves
as a replicate database (in bidirectional replication), you can
remove the LTMLASTCOMMIT table from the primary
database.
Each Replication Agent for DB2 UDB started task can process only one IBM DB2 Universal Database log. Replicating transactions from multiple IBM DB2 Universal Database subsystems (or from multiple data-sharing members in a data-sharing environment) requires one Replication Agent-started task for each IBM DB2 Universal Database subsystem (or data-sharing member).
The following IBM DB2 Universal Database utilities may jeopardize replication integrity if they are executed:
LOAD LOG NO
RECOVER
REORG with RECOVER
The IBM DB2 Universal Database LOAD LOG YES utility
is supported in Replication Agent for DB2 UDB.
