Teradata Parallel Data Pump

Chapter 2: Using Teradata TPump
Writing a Teradata TPump Job Script
different from the database being modified, thus allowing tables to be created and dropped
with no impact on the production database.
In addition, the BEGIN LOAD command establishes acceptable threshold levels for
important task controls, such as number and percentage of errors, session limits, duration
of logon attempts in hours (tenacity), and checkpointing frequency. This command also
provides optional controls to:
• determine where any macros are placed
• guarantee serial operations on given rows
• select the number of statements to pack into a multiple-statement request
• select a restart logic mode
• The next item appearing in a script is usually a description of the records in the external
file containing the change data for the target tables. The description of these input records
appears in a sequence of commands headed by the LAYOUT command.
The LAYOUT command tags the record layout being depicted with a unique name, which
is then referenced by subsequent script commands in tasks throughout the rest of the job.
The LAYOUT is followed by the supporting information contained in the sequence of one
or more FIELD, FILLER, and TABLE commands.
• Each FIELD command describes a single data item occupying a column in the input row.
These items are described by data type, starting position, length, and several other
characteristics. The FIELD command is used only for those items (columns) relevant to
the current task, which are to be sent to Teradata Database as changes to the target table.
The FIELD command may include the KEY modifier if the column is to be considered part
of the primary index for purposes of serialization.
• Each FILLER command describes a column in the input row in the same way as the FIELD
command. These FILLER fields are never sent to Teradata Database. The FILLER
command, however, identifies those columns which should not be sent to Teradata
Database. Thus, if a sequence of 10 alternating FIELD and FILLER commands is used to
describe 10 contiguous columns in the row, every other column, a total of five columns,
would be sent to Teradata Database.
• The TABLE command identifies any existing table with the same layout as the input. The
TABLE command is used when the changes are being enacted on entire rows, rather than
selected columns.
• The next entry in the script is the DML command, which is followed by the DML
statements INSERT, UPDATE, and DELETE. The DML command creates an identifying
label for the DML statement input, which immediately follows the command. The DML
command also defines an error handling process for handling missing and duplicate rows,
with respect to the error table.
The three DML statements (INSERT, UPDATE, and DELETE) follow the DML command,
and may occur in any order and in any quantity. The INSERT statement is used to place a
complete and entirely new row into the target table.
The UPDATE statement takes the data contents from columns in the input record, as
defined with the LAYOUT, FIELD, FILLER command sequence, and substitutes the data
70 Teradata Parallel Data Pump Reference