Lookup stage: Stage tab (DataStage)

You can specify aspects of the Lookup stage from the Lookup stage: Stage tab.

The Advanced section on the Stage tab allows you to specify how the stage executes. The Link Ordering section allows you to specify which order the input links are processed in.

Properties

Use the Lookup stage properties to specify:

  • A range. To define the lookup on the stream link, select a range in the Apply range to columns field
  • Which reference link (if any) can return multiple rows from a lookup.
  • A condition that should be fulfilled before a lookup is performed on a reference link.
  • What action should be taken if a condition on a reference link is not met.
  • What action should be taken if a lookup on a link fails.

To specify that a link can legitimately return multiple rows:

  • Select the link name from the Multiple rows returned from link list (note that only one reference link in a Lookup stage is allowed to return multiple rows, and that this feature is only available for in-memory lookups).

Advanced

  • 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 Propagate by default. It adopts the setting of the previous stage on the stream link. You can explicitly select Set or Clear. Select Set to request the next stage in the job should attempt to maintain the partitioning.

Link ordering

The link ordering section allows you to specify which input link is the primary link and the order in which the reference links are processed. By default the input links will be processed in the order they were added. To rearrange them, choose an input link and click the up arrow button or the down arrow button.