Usage Notes
A rollforward operation uses a single journal table as its input. Define all tables specified for recovery with the same journal table. ROLLFORWARD can recover all data tables or a subset of the tables that are protected by the same journal table.
Use ROLLFORWARD to rollforward data tables on all or a subset of the AMPs.
Do not execute a rollforward over a data definition statement that changed a table’s structure. If Teradata ARC encounters such a change to a table during a rollforward, the rollforward for that table stops and an error message is placed in the output listing.
When recovering a nonfallback table with unique secondary indexes and an AMP is offline, Teradata ARC invalidates unique secondary indexes on the table. After the AMP returns online, drop and then recreate the unique secondary indexes for that table or use BUILD DATA TABLES on the table.
Using BUILD DATA TABLES is much faster than dropping and recreating the unique secondary indexes.
If the table being recovered has a single after image journal and the recovery operation uses the current journal, do not roll forward data rows on the AMP that are backed up by an AMP that is offline. If the table being recovered has a local single after image journal, it may be recovered only to the last archived data.
If the tables to be rolled forward have a dual after-image journal, then the rollforward operation (by default) uses the journal tables that exist on each AMP to roll forward those AMPs.
When performing a restore and rollforward, bring the affected data tables on the AMPs to their state after a modification. Specific AMP rollforwards are typically performed to do one of the following:
Note: When a PPI table or a Column Partition (CP) table is restored, Teradata ARC automatically executes the Revalidate step during the BUILD phase. The Revalidate process increases the Util version of the table. This is considered to be a structural change to the table. Because of this change, a PPI table or a CP table cannot be recovered using either the RollBack or RollForward operation after it is restored.
chkptname Parameter
To set the point in time that ROLLFORWARD (or ROLLBACK) rolls to, a CHECKPOINT statement must have been previously issued with the same value for chkptname. For example, if CHECKPOINT statements with different checkpoint names (for example, check1, check2, check3) were issued, use the same names in the ROLLFORWARD or ROLLBACK statement. Doing so returns the table to the state it was when each CHECKPOINT statement was originally issued.
If this option is specified, Teradata ARC first scans the journal table for the identified checkpoint. If the checkpoint does not exist, Teradata ARC returns an error.
If an unqualified chkptname is used, and there are multiple checkpoint rows in the journal table with the same name, Teradata ARC uses the first chronological entry made. Note this difference from the ROLLBACK statement, where Teradata ARC uses the last entry made.
Alpha characters in a chkptname are not case sensitive; for example, chkptname ABC is equal to chkptname abc. If this option is not specified, Teradata ARC uses the entire journal table.
PRIMARY DATA Keywords
Use this keyword phrase to reduce the amount of I/O during rollforward. Using this option improves the rollforward performance when recovering a specific AMP from a disk failure.
When a specific AMP is recovered, unique indexes are invalid. Always follow a ROLLFORWARD statement that uses the PRIMARY DATA option with a BUILD statement.
RELEASE LOCK Keywords
With Teradata Database, RELEASE LOCK does not release HUT locks on non-fallback tables with remote single after image journaling when the backup AMP is offline.
DELETE Keyword
Use the NO DELETE keyword phrase to recover selected tables if the balance of the tables will be recovered later with changes in the journal.
Do not specify any DELETE options when using the current journal for the recovery.
ABORT Keyword
The ABORT keyword aborts an all-AMPs roll operation that includes non-fallback tables or single copy journal tables if an AMP is down. This option does not affect specific AMP roll operations.