ALTER TABLE and FALLBACK
When an ALTER TABLE request adds FALLBACK, the operation generates a full‑table scan. To add FALLBACK to a table, all AMPs must be online and operational.
When a table or join index is partitioned, its fallback rows are partitioned the same as its primary data rows. If the primary data rows have a primary index, the fallback data rows have the same primary index. If the primary data rows do not have a primary index, the fallback data rows do not have a primary index.
You can change the FALLBACK properties of a global temporary table definition if and only if there are no materialized instances of that table anywhere in the system. However, when an instance of a global temporary table is materialized, Teradata Database creates it without fallback irrespective of its definition unless there is a down AMP in the system. In that case, and that case only, the table is materialized with fallback if it has been defined to do so.
To enable the file system to detect all hardware read errors for tables and join indexes, you should also set the integrity checking level to ALL (see “Disk I/O Integrity Checking” on page 48).