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  • PowerCenter 10.2 HotFix 1
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Table of Contents

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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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Working with Expressions

Working with Expressions

When you use pushdown optimization, the Integration Service converts the expression in the transformation or workflow link by determining equivalent operators, variables, and functions in the database. If there is no equivalent operator, variable, or function, the Integration Service processes the transformation logic. For example, the Integration Service translates the aggregate function STDDEV() to STDDEV_SAMP() on Teradata and to STDEV() on Microsoft SQL Server. The Integration Service processes any transformation that uses the FIRST() aggregate function because no database supports this function.
The Integration Service logs a message in the workflow log and the Pushdown Optimization Viewer when it cannot push an expression to the database. Use the message to determine the reason why it could not push the expression to the database.
The tables in this section summarize the availability of PowerCenter operators, variables, and functions in databases.