The following table identifies the FNC_Context_t fields that are used by window aggregate functions. If a field is not listed in the table, it is not applicable for window aggregate functions or the field is reserved for future use.
| Fields | Specifies |
|---|---|
| version | the version of the context structure. |
| interim1 | a pointer to the aggregate storage area that saves intermediate results. |
| intrm1_length | the length of interim1. |
| window_size |
|
| pre_window | This value is specified as part of the PRECEDING clause. The value of this field is negative if this points to a row that precedes the current row. This field is not applicable for the cumulative and reporting window types. It is initialized to zero in those cases. |
| post_window | This value is specified as part of the FOLLOWING clause. The value of this field is positive if this points to a row that follows the current row. This field is not applicable for the cumulative and reporting window types. It is initialized to zero in those cases. |
Teradata Database 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