Teradata Parallel Data Pump

Chapter 3: Teradata TPump Commands
UPDATE Statement and Atomic Upsert
Teradata TPump changes this syntax into Atomic upsert syntax by replacing the semicolon
between the UPDATE and INSERT statements with an ELSE keyword to convert the statement
pair into a single Atomic upsert statement.
If user-created macros are used in place of the UPDATE and INSERT statements, Teradata
TPump generates:
EXEC ELSE EXEC ;
because this statement does not conform to Atomic upsert syntax used by Teradata TPump.
Atomic Upsert Examples
This section describes several examples that demonstrate how the Atomic upsert feature
works, including cases where errors are detected and returned to the user. All of the examples
use the same table, called Sales, as shown below:
CREATE TABLE Sales, FALLBACK,
(ItemNbrINTEGER NOT NULL,
SaleDateDATE FORMAT 'MM/DD/YYYY' NOT NULL,
ItemCountINTEGER)
PRIMARY INDEX (ItemNbr);
Assume that the table has been populated with the following data:
INSERT INTO Sales (10, '05/30/2005', 1);
A table called NewSales has the same column definitions as those of table Sales.
Example 1 (Error: different target tables)
This example demonstrates an upsert statement that does not specify the same table name for
the UPDATE part and the INSERT part of the statement.
UPDATE Sales SET ItemCount = ItemCount + 1 WHERE (ItemNbr = 10 AND
SaleDate = '05/30/2005') ELSE INSERT INTO NewSales (10, '05/30/2005',
1);
A rule of an upsert is that only one single table is processed for the statement. Because the
tables, Sales and NewSales, are not the same for the upsert statement, an error is returned to
the user indicating that the name of the table must be the same for both the UPDATE and the
INSERT.
Example 2 (Error: different target rows)
This example demonstrates an upsert statement that does not specify the same primary index
value for both the UPDATE and INSERT parts of the statement.
UPDATE Sales SET ItemCount = Itemcount + 1 WHERE (ItemNbr = 10 AND
SaleDate = '05/30/2005') ELSE INSERT INTO Sales (20, '05/30/2005', 1);
The primary index values for the UPDATE and the INSERT must be the same. In this case, an
error is returned to the user indicating that the primary index value must be the same for both
the UPDATE and the INSERT.
192 Teradata Parallel Data Pump Reference