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  1. Preface
  2. Understanding Pipeline Partitioning
  3. Partition Points
  4. Partition Types
  5. Pushdown Optimization
  6. Pushdown Optimization and Transformations
  7. Real-time Processing
  8. Commit Points
  9. Row Error Logging
  10. Workflow Recovery
  11. Stopping and Aborting
  12. Concurrent Workflows
  13. Grid Processing
  14. Load Balancer
  15. Workflow Variables
  16. Parameters and Variables in Sessions
  17. Parameter Files
  18. FastExport
  19. External Loading
  20. FTP
  21. Session Caches
  22. Incremental Aggregation
  23. Session Log Interface
  24. Understanding Buffer Memory
  25. High Precision Data

Advanced Workflow Guide

Advanced Workflow Guide

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Mapping Variables in Partitioned Pipelines

Mapping Variables in Partitioned Pipelines

When you specify multiple partitions in a target load order group that uses mapping variables, the Integration Service evaluates the value of a mapping variable in each partition separately. The Integration Service uses the following process to evaluate variable values:
  1. It updates the current value of the variable separately in each partition according to the variable function used in the mapping.
  2. After loading all the targets in a target load order group, the Integration Service combines the current values from each partition into a single final value based on the aggregation type of the variable.
  3. If there is more than one target load order group in the session, the final current value of a mapping variable in a target load order group becomes the current value in the next target load order group.
  4. When the Integration Service finishes loading the last target load order group, the final current value of the variable is saved into the repository.
Use one of the following variable functions in the mapping to set the variable value:
  • SetCountVariable
  • SetMaxVariable
  • SetMinVariable
The following table describes how the Integration Service calculates variable values across partitions:
Variable Function
Variable Value Calculation Across Partitions
SetCountVariable
Integration Service calculates the final count values from all partitions.
SetMaxVariable
Integration Service compares the final variable value for each partition and saves the highest value.
SetMinVariable
Integration Service compares the final variable value for each partition and saves the lowest value.
Use variable functions only once for each mapping variable in a pipeline. The Integration Service processes variable functions as it encounters them in the mapping. The order in which the Integration Service encounters variable functions in the mapping may not be the same for every session run. This may cause inconsistent results when you use the same variable function multiple times in a mapping.