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Merge stage: Stage tab (DataStage)

Merge stage: Stage tab (DataStage)

You can specify aspects of the Merge stage by double-clicking the stage and updating properties on the Stage tab in the stage editor.

The Properties section lets you specify what the stage does. The Advanced section allows you to specify how the stage executes.

Properties

The following table specifies the Merge stage properties:
Table 1. Properties
Category/Property Values Default Mandatory? Repeats? Dependent of
Merge Keys/Key Input Column N/A Y Y N/A
Merge Keys/Sort order Ascending/ Descending Ascending Y N Key
Merge Keys/Nulls position First/Last First N N Key
Merge Keys/Sort as EBCDIC True/False False N N Key
Merge Keys/Case sensitive True/False True N N Key
Options/Unmatched masters mode Keep/Drop Keep Y N N/A
Options/Warn on unmatched masters True/False True Y N N/A
Options/Warn on reject updates True/False True Y N N/A

Key

This specifies the key column you are merging on. Repeat the property to specify multiple keys. You can use the Column Selection dialog box to select several keys at once if required. Key has the following dependent properties:

  • Sort Order

    Choose Ascending or Descending. The default is Ascending.

  • Case Sensitive

    Use this to specify whether each merge key is case sensitive or not, this is set to True by default, that is, the values "CASE" and "case" would not be judged equivalent.

  • Sort as EBCDIC

    To sort as in the EBCDIC character set, choose True.

  • Nulls position

    By default columns containing null values appear first in the merged data set. To override this default so that columns containing null values appear last in the merged data set, select Last.

Unmatched masters mode

Set to Keep by default. It specifies that unmatched rows from the master link are output to the merged data set. Set to Drop to specify that rejected records are dropped instead.

Warn on unmatched masters

Set to True by default. This will warn you when unmatched rows from the master link are output to the merged data set. Set it to False to receive no warnings.

Warn on reject updates

Set to True by default. This will warn you when bad records from any update links are rejected. Set it to False to receive no warnings.

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.

Link ordering

The link ordering section allows you to specify which of the input links is the master link and the order in which links input to the Merge stage are processed. You can also specify which of the output links is the master link, and which of the reject links corresponds to which of the incoming update links.

By default the 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.

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