Table of Contents

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  1. Preface
  2. Transformations
  3. Source transformation
  4. Target transformation
  5. Aggregator transformation
  6. Cleanse transformation
  7. Data Masking transformation
  8. Deduplicate transformation
  9. Expression transformation
  10. Filter transformation
  11. Hierarchy Builder transformation
  12. Hierarchy Parser transformation
  13. Hierarchy Processor transformation
  14. Input transformation
  15. Java transformation
  16. Java transformation API reference
  17. Joiner transformation
  18. Labeler transformation
  19. Lookup transformation
  20. Mapplet transformation
  21. Normalizer transformation
  22. Output transformation
  23. Parse transformation
  24. Python transformation
  25. Rank transformation
  26. Router transformation
  27. Rule Specification transformation
  28. Sequence Generator transformation
  29. Sorter transformation
  30. SQL transformation
  31. Structure Parser transformation
  32. Transaction Control transformation
  33. Union transformation
  34. Velocity transformation
  35. Verifier transformation
  36. Web Services transformation

Transformations

Transformations

Dynamic lookup query overrides

Dynamic lookup query overrides

When you add a WHERE clause in a Lookup transformation that uses a dynamic cache, connect a Filter transformation before the Lookup transformation to filter rows that you do not want to insert into the cache or target table. If you do not include the Filter transformation, you might get inconsistent results between the cache and the target table.
For example, you configure a Lookup transformation to perform a dynamic lookup on the employee table, EMP, matching rows by EMP_ID. You define the following lookup SQL override:
SELECT EMP_ID, EMP_STATUS FROM EMP ORDER BY EMP_ID, EMP_STATUS WHERE EMP_STATUS = 4
When you first run the mapping, the
mapping
task builds the lookup cache from the target table based on the lookup SQL override. All rows in the cache match the condition in the WHERE clause,
EMP_STATUS = 4
.
The
mapping
task reads a source row that meets the lookup condition you specify, but the value of EMP_STATUS is 2. Although the target might have the row where EMP_STATUS is 2, the
mapping
task does not find the row in the cache because of the SQL override. The
mapping
task inserts the row into the cache and passes the row to the target table. When the
mapping
task inserts this row in the target table, you might get inconsistent results when the row already exists. In addition, not all rows in the cache match the condition in the WHERE clause in the SQL override.
To verify that you only insert rows into the cache that match the WHERE clause, you add a Filter transformation before the Lookup transformation and define the filter condition as the condition in the WHERE clause in the lookup SQL override.
You enter the following filter condition in the Filter transformation and the WHERE clause in the SQL override:
EMP_STATUS = 4