Use Replication Definitions to Optimize Performance

Use replication definitions to improve the performance of the replication system in a warm standby environment.

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

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.
You can specify whether Replication Server replicates all of a table’s columns or all of a stored procedure’s parameters to the standby database or only those columns or parameters listed in the table or function replication definition.

Create a Replication Definition for Replicating into a Standby Database

To create a replication definition just for replicating into the standby database, use the send standby clause in the create replication definition command.

The replication definition’s primary key and replicate minimal columns setting will be used in replicating into the standby database.

See Replication Server Reference Manual > Replication Server Commands > create replication definition.

Specify a Primary Key

The presence or absence of a table replication definition determines how primary key columns are packed in the where clause for a database. See Primary Key Columns and where Clause Packing in Warm Standy and Multisite Availability Environments, in Replication Server Administration Guide Volume 1 > Manage Replicated Objects Using Multisite Availability > Reduce the Use of Replication Definitions and Subscriptions.

Update Minimal Columns

If you create a replication definition for replicating into a standby database, you can take advantage of another replication system performance optimization— the minimal columns setting.

When you use the replicate minimal columns clause, replicated update and delete transactions include only the required columns. Values for unchanged columns can be omitted from update commands. Omitting the unnecessary columns reduces the size of messages delivered through the replication system and requires Adaptive Server to do less work.

If you are not using replication definitions for replicating into the standby, you can still attain this performance benefit.

Minimal column replication occurs automatically if you have no replication definitions for a table or if you have replication definitions for a table but do not use one for replicating into the standby database.

Specify Columns to Replicate into the Standby Database

If you create a replication definition for replicating into a standby database, you can specify which set of columns to replicate.

Specify send standby or send standby all columns to replicate all the columns in the table into the standby database.
Specify send standby replication definition columns to replicate only the replication definition’s columns into the standby database.

See Replication Server Reference Manual > Replication Server Commands > create replication definition for more information about using the send standby clause with the command.

Specify Parameters to Replicate into the Standby Database

If you create a function replication definition, you can specify which set of parameters to replicate.

Specify send standby all parameters (or omit the all parameters clause) to replicate all the parameters for the stored procedure into the standby database.
Specify send standby replication definition parameters to replicate only the replication definition’s parameters into the standby database.

If a replicated stored procedure has no function replication definition, when the stored procedure is executed, Replication Server replicates all of its parameters from the active database into the standby database. You can create only one function replication definition per replicated stored procedure.

See Replication Server Reference Manual > Replication Server Commands for more information about using the send standby clause with the create applied function replication definition and create request function replication definitioncommands.