Replication Definitions for Improving Performance

A replication definition describes the source table to Replication Server, specifying the columns you want to copy. It may also describe attributes of the destination table. Destination tables that match the specified characteristics can subscribe to the replication definition.

Replication Server does not require replication definitions to maintain a standby database, although using replication definitions can improve performance when you are replicating into a standby database. In addition, create replication definitions on tables that contain approximate numeric datatypes so that the where clause used to construct the SQL statement applied to the standby database does not include these columns. The range and storage precision of approximate numeric datatypes (real, float) is machine-dependent, and may result in the wrong rows being modified, or the correct row not being found.

When you specify that you want to use a replication definition for replicating into a standby database:

Replication Server optimizes updates and deletes by using the primary key defined in the replication definition to generate the where clause.
You can specify whether Replication Server uses the replication definition’s replicate minimal columns setting for replicating into the standby database. This setting indicates whether updates replace the values for all columns or only the columns with changed values.

See the Replication Server Admininstration Guide Volume 1 > Manage Replicated Tables for detailed information on replication definitions.