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

Frame

Frame

The frame determines which rows are included in the calculation for the current input row based on the rows' relative position to the current row. Configure a frame if you use an aggregate function as a window function.
The start offset and end offset describe the number of rows that appear before and after the current input row. An offset of "0" represents the current input row. For example, a start offset of -3 and an end offset of 0 describe a frame including the current input row and the three rows before the current row.
The following image shows a frame with a start offset of -1 and an end offset of 1:
 The Sports row is the current input row. The Arcade, Sports, and Adventure rows are part of the window and have corresponding revenues of 1000, 2000, and 3000.
For every input row, the function performs an aggregate operation on the rows inside the frame. If you configure an aggregate expression like SUM on the frame in the previous image, the expression calculates the sum of the values within the frame and returns a value of 6000 for the input row.
You can also specify a frame that does not include the current input row. For example, a start offset of 10 and an end offset of 15 describe a frame that includes six total rows, from the tenth to the fifteenth row after the current row.
Offsets of
All Preceding Rows
and
All Following Rows
represent the first row of the partition and the last row of the partition. For example, if the start offset is All Preceding Rows and the end offset is -1, the frame includes one row before the current row and all rows before that.
The following image shows a frame with a start offset of 0 and an end offset of All Following Rows:
The current input row is Country. All Following Rows include the following rows: Country, Ethnic, Pop, Rock, Classical, EDM, Hip Hop, and Punk.
If the frame offsets are outside the partition, the aggregate function ignores the frame. If the offsets of a frame are not within the partition or table, the aggregate function processes only the rows within the partition. The function does not return NULL or a default value.
For example, you partition a table by seller ID and you order by quantity. You set the start offset to -3 and the end offset to 4.
The following image shows the partition and frame for the current input row:
 The row with seller ID of 3 and quanity of 15 is the current input row. The rows with seller IDS of 3 and quantity of 10, 15, 20, and 30 are part of the window. Rows with seller IDs of 2,3, and 4 are part of the frame.
The frame includes eight total rows, but the calculation remains within the partition. If you define an AVG function with this frame, the function calculates the average of the quantities inside the partition and returns 18.75.
Consider the following rules and guidelines when you define a frame:
  • LEAD and LAG use the frame that you specify in the function arguments and ignore the frame that you configure on the
    Window
    tab.
  • The start offset must be less than or equal to the end offset.