Multivalued (Array Type) Attributes - Parallel Transporter

Teradata PT allows specification of multiple values for a few operator attributes. Array attribute values can be specified as part of:

• A DEFINE OPERATOR statement
• A reference to an operator in an APPLY statement

The following examples show how specification of an array value for an attribute would appear in a DEFINE OPERATOR statement or an APPLY statement:

VARCHAR ARRAY TraceLevel = [ 'CLI', 'OPER' ]
VARCHAR TraceLevel = [ 'CLI', 'OPER' ]
TraceLevel = [ 'CLI', 'OPER' ]

Observe the following additional guidelines for use of array attributes.

• The Teradata PT compiler ensures that array attributes are assigned array-type (multiple) values and vice versa; multiple values are assigned only to array attributes.
• Array values can be assigned in a series as shown in the following examples:

  VARCHAR ARRAY TargetTable = ['table1', 'table2', …, 'tableN']
  VARCHAR TargetTable = ['table1', 'table2', …, 'tableN']
  TargetTable = ['table1', 'table2', …, 'tableN']

  Using the ARRAY keyword in assigning an array value is optional.

• An array value containing a single member (for example, ['x'] or [2]) is still considered a valid array value. In this case, the array dimension is 1. However, even this single value must be specified through array notation, that is to say, enclosed in [ ].
• To omit some of the values for the array attribute, for example, to assign a first and a third value, but not the second, you can do the following: specify a value of NULL. Following is an example of assigning certain attribute values while omitting others.
  • specify a value of NULL, as follows:

    VARCHAR FILE_NAMES = ['/first', NULL, '/third']

  • specify the omitted value with commas, as follows:

    VARCHAR FILE_NAMES = ['/first', , '/third']

• Following example shows an array attribute value assigned as part of a SELECT statement:

     SELECT * FROM OPERATOR (reader ATTR (FILE_NAMES = ['/first', NULL,'/   third'], MODE = 'read')