Table of Contents

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  1. Preface
  2. Mappings
  3. Mapplets
  4. Mapping Parameters
  5. Mapping Outputs
  6. Generate a Mapping from an SQL Query
  7. Dynamic Mappings
  8. How to Develop and Run a Dynamic Mapping
  9. Dynamic Mapping Use Cases
  10. Mapping Administration
  11. Export to PowerCenter
  12. Import From PowerCenter
  13. Performance Tuning
  14. Pushdown Optimization
  15. Partitioned Mappings
  16. Developer Tool Naming Conventions

Developer Mapping Guide

Developer Mapping Guide

Suggested Parallelism for a Transformation

Suggested Parallelism for a Transformation

If you override the
Maximum Parallelism
run-time property for a mapping, you can define the
Suggested Parallelism
property for a specific transformation in the mapping run-time properties.
The Data Integration Service considers the suggested parallelism value for the number of threads for that transformation pipeline stage as long as the transformation can be partitioned. For example, if you configure the mapping to maintain row order, the Data Integration Service might need to use one thread for the transformation.
If the
Maximum Parallelism
run-time property for the mapping is set to Auto, you cannot define a suggested parallelism value for any transformations in the mapping. If you set the maximum parallelism value for the mapping to Auto after defining a suggested parallelism value for a transformation, the Data Integration Service ignores the suggested parallelism value.
You might want to define a suggested parallelism value to optimize performance for a transformation that contains many ports or performs complicated calculations.
For example, if a mapping enabled for partitioning processes a small data set, the Data Integration Service might determine that one thread is sufficient to process an Expression transformation pipeline stage. However, if the Expression transformation contains many complicated calculations, the transformation pipeline stage can still take a long time to process. You can enter a suggested parallelism value greater than 1 but less than the maximum parallelism value defined for the mapping or the Data Integration Service. The Data Integration Service uses the suggested parallelism value for the number of threads for the Expression transformation.
You can configure the following values for the
Suggested Parallelism
property for a transformation when you override the maximum parallelism for the mapping:
Suggested Parallelism Value
Description
1
The Data Integration Service uses one thread to run the transformation.
Auto
The Data Integration Service considers the maximum parallelism defined for the mapping and for the Data Integration Service. The service uses the lowest value to determine the optimal number of threads that run the transformation.
Default for each transformation.
Greater than 1
The Data Integration Service considers the suggested parallelism defined for the transformation, the maximum parallelism defined for the mapping, and the maximum parallelism defined for the Data Integration Service. The service uses the lowest value for the number of threads that run the transformation.
You can define the
Suggested Parallelism
property in the mapping run-time properties for the following transformations:
  • Aggregator
  • Expression
  • Filter
  • Java
  • Joiner
  • Lookup
  • Normalizer
  • Rank
  • Router
  • Sequence Generator
  • Sorter
  • SQL
  • Union
  • Update Strategy

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