This state enables read access for an application when data is externally copied from the table and must remain unchanged.
For managed sessions, if a table is in a Read-Only state across all Teradata Database systems, Business Continuity Manager rejects the write with an error. If only a single Teradata Database system or a table on a specific Teradata Database system is in Read-Only state, then any write requests remain queued in the Recovery Log to be replayed when the Teradata Database system or table is placed into a Restore state.
If a Teradata Database system enters a Read-Only state, all tables automatically enter a Read-Only state. If a table is read-only on one or more systems and a write occurs on this table (because the table is in read-write mode on at least one other active system), then the Read-Only state is changed to an Interrupted state.
A table may also automatically be placed in Read-Only state if a session encounters an error and the "Read-only on write failure" feature is turned on.
To change a table or system to a Read-Only state, run the SYSTEM FREEZE command. Business Continuity Manager holds any new transactions and waits for any in-flight transactions to close. The Dispatcher holds transactions for the time specified in the HaltTimeout parameter. If successful, the Teradata Database system or table becomes read-only. If an error occurs or if in-flight transactions do not finish successfully during the timeout, the operation aborts and the Teradata Database system or table remains in the Active state.
Use the SYSTEM RECOVER command to change a Teradata Database system or table from the Read-Only state to a Restore state.