Restoring After a Reconfiguration - TARA/ABU

Teradata Archive/Recovery Utility Reference

Product
TARA/ABU
Release Number
15.00
Language
English (United States)
Last Update
2018-09-25
dita:id
B035-2412
lifecycle
previous
Product Category
Teradata Tools and Utilities

Restoring After a Reconfiguration

If AMPs have been added or dropped since the archive was created, restore cluster and specific AMP archives to all AMPs. Reconfiguration redistributes data among AMPs, therefore rows in the archive do not distribute exactly to the AMPs from which the rows came.

When restoring or copying a No Primary Index (NoPI) table to a destination system that has a different number of AMPs than the source system, there is a high probability that the data will be skewed on the destination system after the restore or copy. This is due to the algorithm that is used by Teradata Database to distribute the data rows onto the AMPs for a NoPI table.

When PPI tables are restored after a change in configuration or platform, it is necessary for the primary index to be re-validated prior to using the table. For all-AMP and multi-stream restores, Teradata ARC automatically attempts to perform this revalidation. If a problem occurs, Teradata ARC displays a warning indicating the cause of the failure and continues the restore job. After the restore job completes, the user must attempt to rerun the revalidate step manually for PPI tables by using either of the following SQL statements:

ALTER TABLE <database>.<table> REVALIDATE;
ALTER TABLE <database>.<table> REVALIDATE PRIMARY INDEX;

When Column Partition (CP) tables are restored after a change in configuration or platform, it is also necessary for the table to be revalidated prior to using it. For all AMP and multi‑stream restores, Teradata ARC automatically attempts to perform this revalidation. If a problem occurs, Teradata ARC displays a warning indicating the cause of the failure and continues the restore job. After the restore job completes, the user must attempt to rerun the revalidate step manually for CP tables by using the following SQL statement:

ALTER TABLE <database>.<table> REVALIDATE;

Teradata ARC does not automatically revalidate the primary index for dictionary or cluster backups. Additionally, Teradata ARC does not automatically revalidate if the NO BUILD option is specified on the restore, or if RELEASE LOCK is not specified.

Note: After running the revalidate primary index step, you can no longer execute a ROLLFORWARD or ROLLBACK operation using journal table rows taken on the source system before the restore. This restriction only applies to PPI tables and CP tables.

Order of Restores

To restore a cluster archive to a reconfigured Teradata Database, first restore the dictionary archive and then individually restore each cluster archive to all AMPs. Only one restore operation is permitted at a time.

NO BUILD Option

When restoring cluster archives to all-AMPs, use the NO BUILD option on each cluster restore operation. If the NO BUILD option is omitted, Teradata ARC prints a warning and enables the option automatically. After all the cluster archives have been restored, a BUILD statement will need to be run.

If an all-AMPs archive with nonfallback tables is restored to all AMPs, and the all-AMPs archive is missing an AMP that has a specific-AMP archive, restore the all-AMPs archive using the NO BUILD option. In this case, nonfallback tables are not revalidated. Following completion of the restore of the all-AMPs archive, restore the specific-AMP archive to all AMPs. Then follow this specific-AMP archive restore with a build operation.

Logical vs. Physical Space

When restoring to a target system that is smaller than the source, the database space might be reported as a negative value when the operation finishes. This indicates there is no more logical space, rather than physical space. If this occurs, reduce the perm space for some of the databases created on the system by doing the following:

1 Reduce the maximum perm space of user databases and rerun RESTORE.

2 If negative space is reported again, reset the Teradata Database, run UPDATESPACE to decrease the maximum perm space of user databases and rerun RESTORE.

3 Resize one or more users or databases with the DBSIZEFILE=filename option, described in “RESTORE” on page 221.