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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

Early Selection Optimization Method

Early Selection Optimization Method

When the Data Integration Service applies the early selection optimization method, it splits, moves, or removes the Filter transformations in a mapping. It moves filters up the mapping closer to the source.
The Data Integration Service might split a Filter transformation if the filter condition is a conjunction. For example, the Data Integration Service might split the filter condition "A>100 AND B<50" into two simpler conditions, "A>100" and "B<50." When the Data Integration Service splits a filter, it moves the simplified filters up the mapping pipeline, closer to the source. The Data Integration Service moves the filters up the pipeline separately when it splits the filter.
The early selection optimization method is enabled by default when you choose the normal or full optimizer level in the Developer tool. The Data Integration Service ignores early selection optimization if a transformation that appears before the Filter transformation has side effects. The Data Integration Service cannot determine if the SQL transformation, Web Service Consumer transformation, and Java transformation have side effects. You can configure early selection optimization for these transformations if they do not have side effects.
You can disable early selection if the optimization does not increase performance. The Data Integration Service enables this optimization method by default.

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