Teradata Parallel Data Pump

Chapter 3: Teradata TPump Commands
UPDATE Statement and Atomic Upsert
Usage Notes - Update
Temporal Semantics
The following notes describe how to use an UPDATE statement following a DML command.
An UPDATE statement may also be used in the support environment; normal rules for
UPDATE are followed in that case.
• To update records in a table, the userid that is logged on must have UPDATE privilege for
the table.
• In an IMPORT task, if multiple Unique Primary Index (UPI) columns are specified, the
columns should all be specified in the WHERE clause of the UPDATE statement. In this
case, the WHERE clause is fully qualified, thereby allowing Teradata TPump to avoid table
locks and optimize the processing.
• For Teradata TPump use, if the object of the UPDATE statement is a view, it must not
specify a join. Teradata TPump operates only on single table statements so UPDATE
statements must not contain any joins.
• Only one object may be identified.
• The OR construct can be used in the WHERE clause of a DELETE statement; alternatively,
two or more separate DML statements (one per OR term) can be used, with the DML
statements applied conditionally with the APPLY clause of the IMPORT command. The
nature of the alternatives will usually make one of the methods more appropriate.
• The maximum number of INSERT, UPDATE, and DELETE statements that can be
referenced in an IMPORT is 128. The 128th DML which would cause the insertion of the
DML sequence number of 128 for the DMLSEQ field in the error table could lead to
Teradata Database 3520 error.
• The maximum number of DML statements that can be packed into a request is 2430 . The
default number of statements packed is 20.
• To ensure data integrity, the SERIALIZE parameter defaults to ON in the absence of an
explicit value if there are upserts in the Teradata TPump job.
DML validtime qualifier and NONTEMPORAL semantics are supported. For more
information, see SQL Data Manipulation Language and SQL Data Manipulation Language
Advanced Topics.
Example
The following example describes an input data source containing a series of 14-byte records.
Each record contains the value of the primary index column (EmpNo) of a row of the
Employee table whose PhoneNo column is to be assigned a new phone number from field
Fone.
.BEGIN LOAD SESSION number;
.LAYOUT Layoutname;
.FIELD EmpNum 1 INTEGER;
.FIELD Fone * (CHAR (10));
.DML LABEL DMLlabelname;
UPDATE Employee SET PhoneNo = :Fone WHERE EmpNo = :EmpNum;
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