Unity does not allow sessions on an Unrecoverable Teradata Database system. All tables automatically become Unrecoverable when a Teradata Database system is placed in the Unrecoverable state.
A Teradata Database system or table automatically becomes Unrecoverable
when the following occurs:
- Adding a new Teradata Database system to Unity.
- A Teradata Database system in Active, Standby, or Restore state encounters a data inconsistency during a write request.
- Tables added to Unity through a dictionary deploy also come up as Unrecoverable. The only exception is when the table exists only on one system and that system is in the Active state. In this case, the table is auto-activated once the dictionary deploy finishes.
Unity automatically changes
the state of tables based on a recovery mechanism if tables are in different
states.
For example, you have Unity with two systems, both in an Active state. When a transaction runs, it completes successfully on a system where both tables X and Y are in an Active state. However, on a system where table Y is in an Unrecoverable state, table X automatically changes to an Unrecoverable state.
To change a table or Teradata system to Active from Unrecoverable, use SYSTEM ACTIVATE command.