Sort stage: Options
Use the Options section on the Stage tab to specify how the Sort stage operates.
Sort utility
The type of sort the stage will carry out. Choose from:
- DataStage®. The default. This uses the built-in InfoSphere® DataStage sorter, you do not require any additional software to use this option.
- UNIX. This specifies that the UNIX sort command is used to perform the sort.
Stable sort
Applies to a Sort Utility type of DataStage, the default is True. It is set to True to guarantee that this sort operation will not rearrange records that are already in a properly sorted data set. If set to False no prior ordering of records is guaranteed to be preserved by the sorting operation.
Allow duplicates
Set to True by default. If False, specifies that, if multiple records have identical sorting key values, only one record is retained. If Stable Sort is True, then the first record is retained. This property is not available for the UNIX sort type.
Output statistics
Set False by default. If True it causes the sort operation to output statistics. This property is not available for the UNIX sort type.
Create cluster key change column
This property appears for sort type DataStage and is optional. It is set False by default. If set True it tells the Sort stage to create the column clusterKeyChange in each output record. The clusterKeyChange column is set to 1 for the first record in each group where groups are defined by using a Sort Key Mode of Don't Sort (Previously Sorted) or Don't Sort (Previously Grouped). Subsequent records in the group have the clusterKeyChange column set to 0.
Create key change column
This property appears for sort type DataStage and is optional. It is set False by default. If set True it tells the Sort stage to create the column KeyChange in each output record. The KeyChange column is set to 1 for the first record in each group where the value of the sort key changes. Subsequent records in the group have the KeyChange column set to 0.
Restrict memory usage
This is set to 20 by default. It causes the Sort stage to restrict itself to the specified number of megabytes of virtual memory on a processing node.
The number of megabytes specified should be smaller than the amount of physical memory on a processing node. For Windows systems, the value for Restrict Memory Usage should not exceed 500.
Workspace
This property appears for sort type UNIX only. Optionally specifies the workspace used by the stage.