Using RCP With External Source Stages (DataStage)
Runtime column propagation (RCP) allows IBM® DataStage® to be flexible about the columns you define in a job.
If RCP is enabled for a project, you can define the columns that you are interested in using in a job, but ask IBM DataStage to propagate the other columns through the various stages. So such columns can be extracted from the data source and end up on your data target without explicitly being operated on in between.
External Source stages, unlike most other data sources, do not have inherent column definitions, and so IBM DataStage cannot always tell where extra columns must be propagated. You can use RCP on External Source stages only if you use the Schema File property (see "Schema File" on page Schema File) to specify a schema that describes all the columns in the sequential files that are referenced by the stage. You need to specify the same schema file for any similar stages in the job where you want to propagate columns. Stages that require a schema file are:
- Sequential File
- File Set
- External Source
- External Target
- Column Import
- Column Export