Runtime column propagation property

You can configure a Greenplum Connector stage to automatically add missing columns to the link schema at run time.


Before you can enable runtime column propagation in a stage, runtime column propagation must be enabled for parallel jobs at the project level from the IBM InfoSphere DataStage and QualityStage Administrator.

When the runtime column propagation property is enabled for the Greenplum Connector stage, the connector inspects the columns for the result set of the statement that it is configured to run. Then the connector compares this set of columns to the set of columns that are defined on the output link. If any columns in the result set are not defined on the output links, the connector adds them to the output link. Columns that are on the output link but not in the result set are removed from the link.

To display and enable the Runtime column propagation property, you need to first enable the Enable Runtime Column Propagation for Parallel Jobs option for the current DataStage project in the DataStage and QualityStage Administrator. Then select the Runtime column propagation check box on the Columns page for the output link in the stage editor.


The following examples illustrate how runtime column propagation works.

Assume that the Greenplum Connector stage is configured to fetch data from the data source and provide records on the output link. The examples further assume that the Runtime column propagation check box is selected for the output link.

Suppose there are no columns defined for the output link, and the connector is configured to automatically generate SELECT statement to read from table TABLE1. TABLE1 contains the C1, C2 and C3 columns. The connector generates and runs the statement SELECT * FROM TABLE1 and adds the C1, C2, and C3 columns to the output link.