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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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Null Values

Null Values

You can assign null values to parameters and variables in the parameter file. When you assign null values to parameters and variables, the Integration Service obtains the value from the following places, depending on the parameter or variable type:
  • Service and service process variables.
     The Integration Service uses the value set in the Administrator tool.
  • Workflow and worklet variables.
     The Integration Service uses the value saved in the repository (if the variable is persistent), the user-specified default value, or the datatype default value.
  • Session parameters.
     Session parameters do not have default values. If the Integration Service cannot find a value for a session parameter, it may fail the session, take an empty string as the default value, or fail to expand the parameter at run time. For example, the Integration Service fails a session where the session parameter $DBConnection
    Name
     is not defined.
  • Mapping parameters and variables.
     The Integration Service uses the value saved in the repository (mapping variables only), the configured initial value, or the datatype default value.
To assign a null value, set the parameter or variable value to “<null>” or leave the value blank. For example, the following lines assign null values to service process variables $PMBadFileDir and $PMCacheDir: 
$PMBadFileDir=<null>
$PMCacheDir=