Join stage: Stage tab (DataStage)
The Stage tab for the Join stage enables you to control aspects of the Join stage.
The Properties section lets you specify what the stage does. The Advanced section allows you to specify how the stage executes. The Link Ordering section allows you to specify which of the input links is the right link and which is the left link and which are intermediate.
Properties
| Category/Property | Values | Default | Mandatory? | Repeats? | Dependent of |
|---|---|---|---|---|---|
| Join Keys/ | Input Column | N/A | Y | Y | N/A |
| Join Keys/Case Sensitive | True/False | True | N | N | Key |
| Options/Join stage: Options category | Full Outer/ Inner/Left Outer/ Right Outer | Inner | Y | N | N/A |
Key
Choose the input column you want to join on. You are offered a choice of input columns common to all links. For a join to work you must join on a column that appears in all input data sets, that is, have the same name and compatible data types. If, for example, you select a column called "name" from the left link, the stage will expect there to be an equivalent column called "name" on the right link.
You can join on multiple key columns. To do so, repeat the Key property. You can use the Column Selection dialog box to select several key columns at once if required).
Key has a dependent property:
- Case Sensitive
Use this to specify whether each group key is case sensitive or not, this is set to True by default, that is, the values "CASE" and "case" in would not be judged equivalent.
Join type
Specify the type of join operation you want to perform. Choose one of:
- Full Outer
- Inner
- Left Outer
- Right Outer
The default is Inner.
Advanced
This section allows you to specify the following:
- Execution Mode. The stage can execute in parallel mode or sequential mode. In parallel mode the input data is processed by the available nodes as specified in the Configuration file, and by any node constraints specified on the Advanced section. In Sequential mode the entire data set is processed by the conductor node.
- Combinability mode. This is Auto by default, which allows IBM® DataStage® to combine the operators that underlie parallel stages so that they run in the same process if it is sensible for this type of stage.
- Preserve partitioning. This is Set by default. You can explicitly select Set or Clear. Select Set to request the next stage should attempt to maintain the partitioning.