Protection for a Committed Row
DBQL tables occupy permanent space in database DBC. This means that once a row has been sent to an AMP, its insertion into a DBQL log is safeguarded through the Teradata Database transaction and recovery journaling process.
In addition, the data in every DBQL table is protected with FALLBACK. This means that the data is always available unless two or more AMPs in the same clique fail simultaneously.
Note: Because dictionary tables are permanent, the contents of all logs remain until they are explicitly deleted. When you use DBQL, be sure to move rows from the logs to your own tables on a regular basis to avoid running out of PERM space in DBC. For instructions, see “Maintaining the Logs” in the following section.