Table Requirements for Active Standby Pairs

Before you can create an active standby pair, you must create an object to be replicated.

Tables that are replicated in an active standby pair must have one of the following:

• A primary key

• A unique index over non-nullable columns

Replication uses the primary key or unique index to identify each row in the replicated table. Replication always selects the first usable index that turns up in a sequential check of the table's index array. If there is no primary key, replication selects the first unique index without NULL columns it encounters. The selected index on the replicated table in the active database must also exist on its counterpart table in the standby database.

Note:

The keys on replicated tables are transmitted in each update record to the subscribers. Smaller keys are transmitted more efficiently.

Replicated tables have these restrictions:

• A primary key column cannot have a LOB data type.

• You cannot replicate tables with compressed columns.