The following table identifies the FNC_Context_t fields that are used by window aggregate functions. A field not listed in the table is not applicable for window aggregate functions or is reserved for future use.
| Fields | Specifies | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| version | Version of context structure. | ||||||||
| interim1 | Pointer to aggregate storage area that saves intermediate results. | ||||||||
| intrm1_length | Length of interim1. | ||||||||
| window_size |
|
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| pre_window | Part of PRECEDING clause. Value is negative for row that precedes current row. Not applicable for cumulative and reporting window types. Its initial value is zero in those cases. |
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| post_window | Part of FOLLOWING clause. Value is positive for row that follows current row. Not applicable for cumulative and reporting window types. Its initial value is zero in those cases. |
Vantage sets up the following fields prior to invoking the function. The fields are used to define a window of rows for the function to operate on.
- window_size
- pre_window
- post_window