A port selector is a set of selection rules that determine ports. You reference a port selector in an expression. When the generated ports change in a dynamic mapping, the port selector can contain different ports in it. You can create a port selector in an Expression transformation, a Lookup transformation, or a Joiner transformation. These transformations contain expressions that can reference all the ports in the port selector.

You can configure a port selector in the following mapping objects:

Expression transformation

You can reference a port selector in a dynamic expression. When you reference a port selector in the expression, the expression runs against each port in the port selector. The dynamic expression returns a result to a separate output port for each port in the port selector. If the transformation has multiple expressions that reference port selectors, the transformation returns additional output ports for each expression.

Joiner transformation

You can reference two port selectors in a join condition. Define a port selector for the master group and a port selector for the detail group. The Data Integration Service compares each port in the master group to the port in the detail group based on the order of the ports in the port selector. You can choose one type of operator to compare each pair of ports. Each port selector must have the same number of ports.

For example, you configure a port selector called Master-SelectorX that contains the ports A, B, and C. You configure Detail-SelectorY that contains the ports D, E, F. If the join condition is

Master-SelectorX = Detail-SelectorY

, then the Developer tool creates the following join condition:

A = D AND B = E AND C = F

.

Lookup transformation

You can configure a port selector for the ports in a lookup condition. The Data Integration Service compares each port in the input port selector to a port in the lookup port selector based on the order of the ports in each port selector. Each port selector must have the same number of ports.

Write transformation

You can configure a port selector for the ports in the Write transformation.

When you write data to a relational or Hive target, you can choose to create or replace the target table at run time. You can define a DDL query based on which the Data Integration Service must create or replace the target table at run time. You can also configure a port selector in the DDL query.