alter table Support for Warm Standby

Adaptive Server Enterprise version 12.0 and later allows users to alter existing tables—add non-nullable columns, drop columns, and modify column datatypes.

For Oracle warm standby applications, you need replication definitions to enable replication of user defined datatypes. Replication Agent for Oracle automatically creates replication definition at the time of initialization. In such a scenario, you need to manually create new replication definition or alter existing replication definition to explicitly specify in the replication definition which user defined datatype is being replicated to the standby database.

Replication Server supports table changes resulting from the alter table command when the table has no subscriptions.

In previous releases, when a replication definition was defined for a table, Replication Server always used the column datatype defined in the warm standby replication definition. Beginning with Replication Server version 12.0, and depending on the situation, Replication Server may or may not use a table’s replication definition.

• No Replication Definition
  When you use the alter table command against a table without replication definitions, Replication Server sends warm standby databases the same information it receives from the primary server.
• alter table Add Column with Default
  Learn how to avoid a DSI error when you issue the alter table command in the active database to add a column with a default value.
• Warm Standby with No send standby Clause
  When there is no send standby clause associated with any replication definition, Replication Server sends whatever data it receives from the primary table without referring to the replication definitions.
• Warm Standby with send standby all columns Clause
  When send standby all columns is associated with a replication definition, Replication Server sends whatever data it receives from the Replication Agent using the original column names and datatypes. The replication definition is used only to find the primary key.
• Warm Standby with send standby replication definition columns Clause
  When there is a send standby replication definition columns clause in the replication definition, the standby will continue to use the replicate table name and column names as well as the datatype defined in the table’s corresponding replication definition.