Teradata Parallel Data Pump

Chapter 1: Overview
The Teradata TPump Task
Task Limits
Teradata TPump supports only single-row, primary index operations. Up to 2430 of these
operations can be packed into a single request for network efficiency. The 2430 - statement
upper limit is arbitrary and may actually be lower for statements associated with large data
parcels that may exceed the overall limit of 64 KB for a request, or where a statement itself is
very long.
DML Commands
Upsert Feature
Teradata TPump Macros
DML commands appear with their associated INSERT, UPDATE, or DELETE DML
statements, together with the IMPORT commands that identify data to be read from the
client.
Teradata TPump DML statements support a conditional apply logic similar to MultiLoad, in
which DML statements are applied based on record field contents.
Specified DML statements following a DML command apply data from one or more separate
data sources. The data sources contain a record for each table row to which one or more
statements apply. Each IMPORT command identifies a separate data source, and references
LAYOUT and DML commands. The IMPORT command matches records of the data source
to the applicable DML statement or statements by means of its APPLY clauses.
The LAYOUT command defines the layout of the records of a data source, using the
parameters and a sequence of FIELD, FILLER, and TABLE commands. The DML command
identifies an immediately following set of one or more DML statements.
Each DML statement is converted into a macro and used for the duration of the import.
As Teradata TPump reaches the end of one data source, as identified by the IMPORT
command, it continues with the next IMPORT command.
Teradata TPump’s upsert feature is a composite of UPDATE and INSERT functionality applied
to a single row. Teradata TPump upsert logic is similar to that used in MultiLoad, the only
other load utility with this feature. The DML statements required to execute each iteration of
upsert are a single UPDATE statement, followed by a single INSERT statement.
With upsert, if the UPDATE fails because the target row does not exist, Teradata TPump
automatically executes the INSERT statement. This capability can save considerable loading
time by completing this operation in a single pass instead of two.
Before beginning a load, Teradata TPump creates equivalent macros on the database, based on
the actual DML statements. That is, for every INSERT, UPDATE, DELETE, and UPSERT
statement in the DML statement, Teradata TPump creates an equivalent macro for it. These
macros are then executed iteratively, in place of the actual DML statement, when an import
task begins, and are removed when all import tasks are complete. The use of macros in place
of lengthy requests helps to minimize network and parsing overhead.
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