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.
For greater efficiency, Teradata TPump also supports the use of predefined macros, rather than creating macros from the actual DML statements. A predefined macro is created by the user and resides on the database before a Teradata TPump import task begins. When a predefined macro is used, Teradata TPump uses this macro directly instead of creating another macro. The use of predefined macros allows Teradata TPump to avoid the overhead of creating/dropping macros internally, and also to avoid modifying the data dictionary on the database during the job run.
Teradata TPump uses the EXECUTE command to support predefined macros. For more information on using predefined macros, see EXECUTE. For more information about creating a macro, see Teradata Vantage™ - SQL Data Definition Language Detailed Topics , B035-1184 .
For more information about executing a macro, see Teradata Vantage™ - SQL Data Manipulation Language, B035-1146.