Advanced tab

All stage editors have an Advanced tab. The Advanced tab allows you to do the following tasks:

• Specify the execution mode of the stage. This allows you to choose between Parallel and Sequential operation. If the execution mode for a particular type of stage cannot be changed, then this drop down list is disabled. Selecting Sequential operation forces the stage to be executed on a single node. If you have intermixed sequential and parallel stages this has implications for partitioning and collecting data between the stages. You can also maintain the default setting for the stage (the drop down list tells you whether this is parallel or sequential).
• Set or clear the preserve partitioning flag (this field is not available for all stage types). It indicates whether partitioning is preserved at the next stage of the job. You choose between Set, Clear and Propagate. For some stage types, Propagate is not available. The operation of each option is explained in the following list:
  • Set. Sets the preserve partitioning flag. This flag indicates to the next stage in the job to preserve existing partitioning if possible.
  • Clear. Clears the preserve partitioning flag. Clear does not specify which partitioning method the next stage can use.
  • Propagate. Changes the flag to Set or Clear depending on what the previous stage in the job has set (or if that is set to Propagate the stage before that and so on until a preserve partitioning flag setting is encountered).

    You can keep the default setting for the stage (the drop down list tells you whether this is set, clear, or propagate).

• Specify the combinability mode. Under the covers InfoSphere® DataStage® can combine the operators that underlie parallel stages so that they run in the same process. This saves a significant amount of data copying and preparation in passing data between operators.

  The combinability mode setting tells InfoSphere DataStage your preferences for combining for a particular stage. It has three possible settings:

  • Auto. Use the default combination setting.
  • Combinable. Ignore the operator's default setting and combine if at all possible (some operators are marked as non-combinable by default).
  • Don't Combine. Never combine operators.

    In most cases the setting should be left to Auto.

• Specify node map or node pool or resource pool constraints. The configuration file allows you to set up pools of related nodes or resources. The Advanced tab allows you to limit execution of a stage to a particular node or resource pool. You can also use the map to specify a group of nodes whose execution is limited just to this stage.
  • Node pool and resource constraints. Specify constraints in the grid. Select Node pool or Resource pool from the Constraint drop-down list. Select a Type for a resource pool and select the name of the pool to which you are limiting execution. You can select multiple node or resource pools. This is only enabled if you have defined multiple pools in the configuration file.
  • Node map constraints. Select the option box and type in the nodes to which execution is limited in the text box. You can also browse through the available nodes to add to the text box. Using this feature conceptually sets up an additional node pool which doesn't appear in the configuration file.

    The lists of available nodes, available node pools, and available resource pools are derived from the configuration file.