Teradata Parallel Data Pump

Chapter 2: Using Teradata TPump
Restart and Recovery
Caution:
Do not tamper with the contents of the restart log table. A missing or altered restart log table
will cause the Teradata TPump job to be recovered incorrectly.
Basic Teradata TPump Recovery
Whenever a database restart is detected or a Teradata TPump job is restarted on the host
system, the following activity occurs:
• The restart log table is scanned with reference to the Teradata TPump script. Each
statement within the script is either executed because a row does not exist or ignored
because a row exists in the restart log.
• In the case of the END LOAD statement, there are a number of rows which are placed in
the restart log table which let Teradata TPump decide what to do. Teradata TPump ignores
any complete IMPORT within a LOAD and begins at the incomplete IMPORT.
• Within an unfinished IMPORT, Teradata TPump begins processing at the last complete
checkpoint. If the Teradata TPump job was running in SIMPLE mode before the restart,
then recovery is complete and processing continues at the last complete checkpoint.
• If Teradata TPump was running in ROBUST mode before it was restarted, then Teradata
TPump must next ascertain how much processing has been completed since the last
checkpoint. This is accomplished by reading back a set of “Partial Checkpoints” from the
restart log table in Teradata Database, sorting them, and then reprocessing all transactions
which were left incomplete when the job was interrupted.
Protection and Location of Teradata TPump Database Objects
The restart log table is critical to the recovery process. If the restart log table is dropped, there
is no way to recover an interrupted Teradata TPump job.
In addition to the restart log table, Teradata TPump also creates an error table and a number
of macros (where each macro corresponds to a DML SQL statement involved in current
IMPORT). If these database objects are dropped, they can, with some effort, being recreated.
However, it is much more convenient for this NOT to be necessary.
Teradata TPump does not have special locks that it places on database objects. It is important
that administrators take security precautions to avoid the loss of these objects.
If the objects are dropped accidentally, the following information should allow an
administrator to recreate them.
Teradata TPump macros are placed in the same database that contains the log restart table.
The macros are named according to the following convention:
Jobname_DDD_SSS
where
• Jobname is the job name, which, if not explicitly specified, defaults to:
MYYYYMMDD_HHMMSS_LLLLL.
• LLLLL is the low-order 5 digits of the logon sequence number returned by the database
from the .LOGON command.
Teradata Parallel Data Pump Reference 53