Specifying Data Protection
Specific protection for the data in a table is provided by the FALLBACK, JOURNAL, and CHECKSUM options.
FALLBACK causes a duplicate, or fallback, copy to be maintained by Teradata Database. The fallback copy is used if the primary copy becomes unavailable.
JOURNAL provides data protection through system‑generated BEFORE‑ and AFTER‑journals that contain the before and after images of data that changes as a result of any INSERT, UPDATE, or DELETE operations.
These journals are used by Teradata Database either to restore a table or to roll back the changes that were made to a table.
The CHECKSUM option implements disk I/O integrity checking of primary table data rows, fallback table data rows, and secondary index subtable rows at various user‑specified or system‑wide levels.